.....using SFC coded-card key interlock systems.TESTED, TRIED & TRUSTED

Mechanical Control

Systems for Process

Pipeline & Maintenance

Operations

ContentsProfile

Safety and Clients

Principles

Products

Applications

From an initial site visit

for risk assessment, to

system design and finally

installation.

34

68

20

Smith Flow Control (SFC) was established in 1985 to provide engineered

safety solutions for hazardous operations in the oil & gas and chemical processing

industries.

SFC introduced the coded-card linear-key concept in a range of modular key-operated

interlocks to regulate operator execution of work procedures on any form of host process

equipment. Typical applications include every form of valve (including motorised and

instrument valves), switches, vessel closures, access guards, pressure and temperature

sensing systems and rail/road/sea tanker loading systems.

SFC’s solutions in hazardous processes reduce the

scope for operator error and ensure safe continuous

plant operation.

Most offshore installations in the North Sea have been

equipped with SFC systems as well as the majority of

related onshore processing facilities throughout Europe. By 1990, SFC became the

generic term for key interlock safety systems in the international oil & gas industry and our

client base now includes most of the major operating companies in all five continents.

In 1990 SFC became part of Halma plc (quoted on the London Stock Exchange) and in

1993 acquired ISO 9001 accreditation certified by Lloyds Register.

Today SFC continues to be managed by its founders who remain committed to providing

quality assured products delivered on time at a competitive price. SFC employs 50

people including 3 design engineers dedicated

full time to product development, using 3D

modelling, a full-time quality manager and 2

full-time works quality inspectors. Our

manufacturing design office is staffed by

8 design engineers who are all highly

trained in the capabilities of AutoCAD

2000 which is our chosen state-of-the-art

manufacturing design tool.

SFC maintains a crew of 4 full time fully

certified site technicians which enable us

to ofter total turn-key services to our clients.

Company profile and objectives

Mike (M.J.) Smith - Vice-Chairman who

co-founded the company in 1985 has

been involved in the international oil &

gas industry for 25 years.

‘....for over 15 years SFC have never failedto provide a viable technical solution to aclient’s safety operating problem....’

3

4

As a general principle it may be said that operations which are safe when

performed correctly can have catastrophic consequences when performed incorrectly.

The Oil & Gas and ChemicaI processing industries generally have a disciplined

approach to design and operating practice - usually governed by well recognised

international standards and enforced by regulatory authorities and certification bodies.

While good practice begins with good design - both are ultimately hostage to the

'Human Factor'.

Modern process plants are highly automated and

regulated by distributed software management

systems which are simply monitored by 'Production'

personnel - often remote from the physical location

of the plant itself. Indeed, some irregular operations

such as pig launching or receiving procedures can

be effected in semi-automatic mode using push-

button controls (again often from a remote station).

Maintenance procedures however invariably

involve human intervention and interrupt automated

processes creating 'abnormaI' conditions for the

duration of the work. Loading or unloading of pig

traps, changeover of pressure relief valves, turbine

servicing (requiring suspension of C02 Fire Deluge),

coupling or uncoupling of hoses for loading

or discharge of tanker cargoes all involve

human intervention and are hostage to the

possibility of operator

error.

Distributed control

systems (DCS)

cannot effectively

regulate such

(maintenance)

procedures - the SFC

‘Coded Card Key

Interlock System' can!

To say working practices have

changed in recent years is an

understatement. Safety was

something that was addressed

only when somebody was

killed or injured, whereas

today prevention has assured

that fatalities and serious

injury figures have dropped

dramatically

Eliminating chance in industrial environments

Potentially LPG storage tanks are one of

the most dangerous areas of the petro/gas

industry, but with the correct safety system

the hazard is kept to the minimum.

Jonathon Hildrey -Financial Director whojoined SFC in 1993 isa qualified CharteredAccountant and aComputer Sciencesgraduate fromCambridge University.

5

SFC hold many client commendations for outstanding performance and are always

pleased to make these available to interested prospective clients.

A significant proportion of our business is repeat work with long-standing clients with

whom we enjoy ‘preferred vendor’ status.

SFC are the only valve interlock manufacturer who can demonstrate total product

reliability, field proven over 15 years.

The reliability of our products is second to none. The satisfaction of our clients is proven.

SFC serve industry by eliminating human error and reducing the opportunities for

procedure violations.

SFC are registered with the ‘Achilles’ and ‘1st Point’ vendor databases and are

accredited to ISO 9001 by Lloyds and are certified also by TÜV.

It would be difficult to name aparticular industry that would notbenefit from an SFC coded-card keyinterlock system.

Global market interests

Elf

Exxon

Fina Neste

Foster Wheeler

Gas Authority of India

Hitachi Zosen

Hoechst

Hyundai Heavy Inds. Co Ltd

ICI

JGC Corporation

Kvaerner Process

John Brown Eng. & Cons. Ltd

Karachaganak Petro. Op. B.V.

Kvaerner Oil & Gas

Lasmo Nederland B.V.

Linde A.G.

Maersk

Marathon Oil UK

Mitsui

Mobil

Montell Carrington

M W Kellogg

Natco

National Petroleum Con. Co.

NAM

Neles - Jamesbury

Norsk Hydro

Nynas UK

Occidental Petroleum

Petrobras

R M Parsons

Repsol

Apart from the big users of key exchange

interlocks in the power, industrial,

commercial and petrochemical sectors, a

large market for these systems exists in the

small and medium scale industries (SMIs).

Adnoc

AAF

ABB Lummus Global

ADMA-OPCO.

Agip

Air Products

Aker

Amerada Hess

Amec

BP Amoco

AOC International

Arco British

A/S Norske Shell

Azerbaijan Int. Op. Co.

Bayer

Babcock Water

Baker Hughes

Barmac

BASF

Bechtel

BG Exploration

BHP Petroleum

BOC Process

Borealis Polymers

BP Oil

British Nuclear Fuels

British Gas

Britoil

Brown & Root

BHP Petroleum

Butagaz B.V.

Calor Gas

Chevron

Chiyoda

CIBA

Conoco

Costain

Daelim

Daewoo

Doha Petroleum

Dong Ah Consortium

DOW

DSM

Du Pont

Pennzoil

Petroland

Petronas Gas BHD

Phillips Petroleum

Preussag Fire Protection

Q.G.P.C.

Saudi Basic Industries Corp.

Saga Petroleum

Samsung Engineering

Score (Europe)

Scottish Nuclear

Scomark Engineering

Shell (UK) Expn & Prodn

Single Buoy Moorings Inc

SLP Engineering

Smithkline Beecham

Snamprogetti Spa

Sable Energy Corp.

Statoil A/S

Sasol

Stone & Webster Engineers

Technipetrol Spa

Terra Nova Alliance

Texaco

Technip

Total Oil Marine

Umoe Olje OG Gass AS

Union Carbide

Whessoe LGA Gas Tech.

Wintershall

Wood Group Engineering

Woodside Petroleum

Transfield Worley Eng.

Wormald Engineering

Zeneca

6

“you only get one chance in this game!”

Controlling the sequence of events in which process activities are conducted

has been achieved historically using a Permit to Work (PtW) accompanied by documented

instructions.

However, this system is hostage to ‘human factors’. Distractions, failure to interpret

correctly, ignorance of the system - all can lead the operator to make errors which can

manifest themselves in industrial accidents of varying magnitudes.

Trapped Key Interlocks are simple mechanical devices which can be customised to

implement a safe sequence of operation in any process activity.

In the following pages we show how our mechanical key interlock system ensures that pig

trap valves are disabled and proven shut and the vessel is isolated, drained and vented

BEFORE opening of the closure for loading or unloading of pigs, or, how the spare pressure

safety relief valve is on stream BEFORE an in-service relief valve can be isolated and

removed, or, how we prevent a tanker from departing a loading/discharge station BEFORE

the cargo hoses are disconnected.

These and any other work tasks executed by human intervention can be completely

regulated by SFC's coded-card key interlocks - simple and total mechanical reliability to

prevent operator error or violation to protect your plant, the surrounding community and the

environment.

In addition to our range of high-integrity coded-card key interlock safety products, SFC

also offer a comprehensive range of valve and process equipment security products for high

and low-criticality applications.

BE SURE - BE SAFE - CHOOSE SFC - YOUR PARTNER

FOR TOTAL PLANT SAFETY & SECURITY.

The principles of interlocking

With the simple act of retrieving a key from

the central key cabinet, a sequence of

events is initiated that eliminates chance or

any one person gambling on an action that

may or may not work.

The hazards of the sea are bad

enough but the hazards of loading

and unloading thousands of tons

of LNG presents another set of

dangerous activities. With SFC

safety systems in place, ships and

their crews enjoy maximum safety.

7

In 1988, the Piper Alpha platform sustained a

devastating explosion and loss of life that

could and should have been prevented.

In the ensuing enquiry the Cullen Report*strongly recommended that all PtW systems

should incorporate mechanical locking

arrangements.

*The Public Enquiry into the Piper Alpha

Disaster by The Right Hon Lord Cullen

presented to Parliament Nov. 1990

Mike D’Anzieri -Managing Director andco-founder of thecompany has over 20years experience inmarketing andmanufacturing ofindustrial safetyproducts.

8

Interlocks for Lever and Handwheel Manually Operated Valves

'QL' - Compatible with:1. Ball valve

2. Butterfly valve

3. Plug valve

PRODUCTS

1 2 3

These illustrations show our basic

product range - the 'QL' interlock for 90o

quarter-turn lever-operation ball, butterfly

or plug valves - and the 'GL' interlock for

handwheel-operated gate, globe and gear-

operated valves.

Each of these lock models are available

with purpose-machined mounting

couplers, or with universal mounting kits

(where the valve topworks details may be

difficult to obtain). For each lock model

('QL' or 'GL') the universal mounting

arrangement is denoted with the suffix

'U' - e.g. 'GLU'.

All SFC products are manufactured from

316 stainless steel material and are supplied

with manufacturers' Certificate of Conformity

to BS EN 10204: 1991 Section 2. 1.

Standard modular products are

manufactured as lost wax investment

castings - 'specials' may be machined

from 316 stainless steel bar stock.

Every interlock assembly is protected

with stainless steel self-sealing

weatherstrips fitted to the key entry

apertures to prevent the ingress of dirt into

the internal lock mechanism.

SFC interlocks are operated using the

'Coded Card Key' design developed

originally by SFC in 1985 - today there are

thousands of units installed and working

successfully in most of the major oil/gas

provinces worldwide. Despite attempts by

others at producing cheap imitations - SFC

products are most-preferred by clients -

our name remains a byword for quality and

reliability.

Type 'QL' with purpose-machined mounting coupler for direct mounting

onto spindle of specifically nominated valve.

Type ‘QLU’ with universal mounting kit for adaption to non-specific

lever-operated 90o ball, butterfly or plug valve.

9

4

PRODUCTS

21

3

'GL' - Compatible with:1. Rising Stem Gate Valve

2. Rising Handwheel Globe Valve

3. Gear-Operators

4. Diaphragm Valve

• All 316 stainless steel.

• Fire rated to 700oC.

• Ultra-low temperature tested to -57oC.

• Destructively tested to extreme parameters.

• Sea-salt spray mist tested.

• Grit-blast tested.

• Thousands of units field proven over 15 years.

• Adapt to any valve without any modificationto the host equipment - no welding / no drilling / the certified pressure envelope of the host valve is never compromised.

• Retro-fit to live plant without the need for shutdown.

• High integrity mechanical control system.

• Ergonomic design.

• Coded Card, Linear Key concept.

Type 'GL' with purpose-machined mounting coupler for direct mounting

onto yoke or shaft of specifically nominated valve.

Type ‘GLU’ with universal mounting kit for adaption to non-specific

handwheel-operated gate, globe, diaphragm or gear operated valve

10

Having implemented a good key

interlock control system, the next most

important step is to apply a good Key

Management System.

For storage, ease

of access and issue,

SFC key cabinets

provide all that is

required.

A key cabinet

should be located in

a safe place; typically

a control room

whereby initiating

keys are issued by

the Shift Supervisor,

Offshore Installation

Manager (OIM) or

other person in

authority.

Cabinets vary in

size and can

accommodate from 1

- 227 system initiating

(or spare) keys. Keys

can be located via

means of hooks or

holsters. (The holster

locator provides

increased capacity).

Each interlocked

system has a

dedicated engraved

tag location within the key cabinet. During

periods of normal operations, all interlock

system ‘permit’ (initiating) keys are visually

displayed within the cabinet in dedicated

locations.

Each key cabinet tag is engraved with

the relevent piping package data - this

same data is also replicated on each

system key.

Key Cabinets

PRODUCTS

When the key is removed, a ‘Visual Alert’

tag is revealed providing details of the key

which has been issued, its designated

location, and the words ‘WORK IN

PROGRESS’.

Control Room staff have clear and easy

indication of work status at any time.

Key cabinets can also accommodate

mimic diagrams. These are extracts of the

P&ID diagram engraved onto a Traffelite

plaque and show clear details of all valves

which are interlocked.

Design Features and User Benefits

• Carbon or Stainless Steel construction.

• ‘Glazed’ door provides key status

without the need to open.

• Ingress Protection from IP55 to IP66.

• Lockable Doors.

• External wall mounting brackets.

• Total integrity by using dedicated

(coded) key locations.

• Complete key status awareness.

11

PRODUCTS

Manufactured as standard to IP55

specification. Higher IP ratings are

available to special order. Locked

door ensures that the total

operational control of interlock

systems resides with the

Designated Authority.

Constant visual indication of

effective management of Permit to

Work procedures.

‘Work in Progress’ status indicated by

the removal of a procedure initiation permit

key. Additional detailed process

description also revealed to indicate where

work is taking place. Key tags can be

colour co-ordinated with mimic graphics.

Gloria Young -Shipping Clerk whohas been with SFCsince 1993

Jackie West - ProjectsCo-ordinator has beenwith SFC since 1990and is responsible forproject documentationand management ofsite services.

12

Where valves are actuated by means of

Pneumatic, Hydraulic, Gas or Electrical

power sources SFC interlocks can be

integrated into the actuator operation to

provide complete manual control of the

valve.

The same basic principles of

interlocking apply; establish and prove the

desired position of the valve and

immobilise the valve in that position. For

actuated valves, there may be two or more

means of operating the valve and all need

to be accommodated within the interlock

scheme.

The high torque applied during valve

actuation means that physical

(mechanical) locking of the valve operating

motion is not practicable.

Instead, mechanical interlocking of the

actuator control mechanism is the

preferred method.

ELECTRICAL ACTUATORS

1. A mechanical interlock placed over the control

push button station (SLU) prevents operation of

the controls without the permit key.

2. An ‘actuator key exchange’ (AKE) unit placed

over the gearbox or valve stem provides

mechanical valve status indication *.

3. A multi-turn interlock fitted to the manual

override handwheel (HWL) prevents the

Interlock scheme being overridden manually.

*It is imperative to ensure the valve has reached

its fully open, or fully closed position before

proceeding to the next stage of the interlock

sequence. The AKE unit provides ABSOLUTE

proof of valve status.

PNEUMATIC ACTUATORS

Pneumatic actuators normally operate on a

'spring return - fail safe' principle. Interlocking

such vaIves simply requires the introduction of a

small diameter 3-way ball valve into the

pneumatic power line. This valve is locked in the

open position - (power 'ON' - valve

'ENERGISED'). Unlocking the interlocked 3-way

valve permits the air supply to be ‘vented' through

the 3rd port - simulating power failure which will

cause the actuator to move the process valve to

its open or closed fail-safe position.

Actuators

PRODUCTS

'AKE' Actuator key

exchange unit.

'SLU' Switch lock unit.

'HWL' Manual override

handwheel unit.

HWL

SLU

AKE

HYDRAULIC ACTUATORS

Hydraulic actuators simply require the

introduction of an interlocked

block valve in the power line

sited between the field control

cabinet and the actuator

itself. This unit is interlocked

with an 'AKE' unit positioned

on the valve gearbox - after

operation, the hydraulic power supply

line valve is unlocked and closed and then

locked closed to release a key which is

exchanged through the 'AKE' unit to confirm

the main valve's new position.

13

Access into pressure vessels is a

potentially hazardous exercise. Residual

pressure, volumes of residual liquids or

gases all can be harmful - typical

examples of these potential hazards

include pig traps, slug catchers and filter

housings.

Locking the vessel closure in the closed

position ensures access into the vessel

can be achieved only under controlled

safe conditions. The operating key is held

in a secure place - e.g. Control Room or

Supervisor's office or is retained (trapped)

in some other related interlocked item of

equipment.

As a minimum, vessel closures are

usually interlocked with vessel venting and

draining functions - the interlocking

arrangement can be extended to

incorporate all process items of equipment

relating to the vessel’s function.

The SFC 'DL3' interlock is adaptable to

all types of vessel/access closures and is

very simple to use. In pig trap applications

where the closure incorporates a bleed

device, the 'DL3' interlock will be

designed to interface with the bleed

function to ensure the bleed screw cannot

be removed until the interlock permit key

has been inserted to unlock the 'DL3'

assembly.

When the 'DL3' is incorporated into

vessel access safety procedures, total

equipment and personnel safety is assured.

Any type of closure can be fitted

with the DL3 interlock, regardless

of their method of operation.

Design details can be provided on

request.

Closures

PRODUCTS

Chris Tonks - SalesOffice Manager has

been with the companysince 1992 and is

responsible for projectmanagement of all major

project orders.

14

Specials

PRODUCTS

Road Barrier Interlock

Customer Problem:

To prevent product spillage and damage to loading equipment as a

result of vehicle drive-away during loading.

SFC Solution:

Where any liquid gas or powder product is being transferred from store

to tanker or vice-versa, an interlocked road barrier will ensure spillage

cannot occur as a result of vehicle drive away.

Regardless of whether the product is hazardous or not, if it is spilt, there

may be expensive consequences.

With an interlock system in place a driver who has forgotten to

disconnect product transfer lines cannot vacate the loading point until the

road barrier is raised. However, the barrier is locked down and the

operating key is trapped in either the transfer valve lock or hose storage

container.

Only when these have been closed, or locked away can the key be

retrieved to unlock and raise the barrier, permitting drive away.

The range of process applications to

which SFC interlocks can be applied is

unlimited. As clients begin to understand

the immense operational capabilities of

SFC interlock systems, they often request

unique solutions to specific problems.

In this section we present some

examples of ‘specials’ we have developed

to meet clients’ specific operating safety

requirements.

SFC are always pleased to receive a

challenge to provide unique solutions to

clients’ individual or special problems.

Tony Griggs - ProjectEngineer has been with

SFC since 1995 and isresponsible for SFC

business with associateGroup companies andagents/distributors in

Australia and USA.

15

Specials

PRODUCTS

Modular Control Panel

Customer Problem:

To provide complete visual positional status of motor operated valves

(MOV's) during each stage of a pigging procedure from a single location.

SFC Solution:

Complex pig launcher and receiver systems comprising Motor Operated

Valves (MOV's) sometimes require full 'visual aware/control' status.

This modular, locally mounted control panel comprises full graphical mimic

board with status beacons on critical valves. Below the graphic board,

interlocked hazardous area control switches, providing power isolation to the

MOV's are situated for easy operation.

The entire panel is protected with a stainless steel canopy.

Flare System Protection

Customer Problem:

To ensure high-pressure gas compressors are shut

down prior to isolating flare system Pressure Safety

Valves (PSV's).

SFC Solution:

An electro-mechanical interlocked soleniod control

switch which releases the PSV interlock system permit

key ONLY after the compressors are shut down and

isolated. The compressor can be either single or double

ended - whichever is the case, all sides have to be

isolated PRIOR to key release.

Electro-mechanical unit incorporates indication of

compressor power isolation for key release - this

indication also includes a signal to the Control Room that

the key has been removed. These functions can be

designed to meet customers' specific requirements - the

unit illustrated is for 3 compressors (one double-ended

and two single units).

Ian Binney - Project Engineer and agraduate in Chemical Engineering has

been involved in safety engineering forover 17 years and is responsible forSFC business with major clients in

Japan, the Middle East, South Africaand Latin America.

16

Specials

PRODUCTS

Customer Problem:

To provide a visual signal from the remote

pig launcher door to the central control

room that the end closure is open.

SFC Solution:

Our DL3 interlock is used to secure all

types of vessel closure. In this illustration,

the interlock was fitted to a Pig Receiver to

ensure complete isolation, venting and

Customer Problem:

Restrictions of space require that a

modular style double block and bleed

valve is used in place of a conventional

3 valve piped arrangement. It is

required that the modular valve is

interlocked with other valves in the

system.

SFC Solution:

Modular valves of this type pose greater

problems for interlocking by virtue of their

Customer Problem:

To convert remote valve operation

(motorised valves) to local operation, and

still retain the integrity and safety of the

operating sequence.

SFC Solution:

For this problem, our solution was to

design and manufacture a solenoid key

release device. As a consequence of the

working environment, a hazardous area

enclosure to Eexd IIb T6 was also required.

size and space limitations.

SFC designed a bespoke

cam type interlock

espec ia l l y fo r th i s

host valve.

Used on the Brent Delta

platform, this interlock

provided the perfect solution to

our customer’s problem.

draining procedures were correctly

executed before the door was opened.

A proximity sensor was bolted to the

interlock casing and the sensor positioned

to detect the key being inserted into the

lock.

Positional indication can be provided

on our complete range of interlock

products.

The basic 'QL' lock body was fitted to the

operating lever (knob) of the switch.

BASEEFA certification for this adaptation

was approved.

A remote signal from the control room

activates the local solenoid which releases

the key. The key is used to operate other

valve control equipment in the system.

A proximity sensor fitted to the switch lock

provides evidence back to the control

room that operational activity is underway.

DL3 Interlock C/W Proximity Sensor

Modular Double Block & Bleed Valves

Solenoid Key Release Device

17

Simple Valve Lock

Customer Problem:

To prevent tampering of valves on utility supplies, e.g. water, gas etc.

SFC Solution:

A 'fully fledged' valve interlock might normally be prohibitively

priced so a purpose designed interlock has been developed

specifically for these applications.

This simple device can lock the valve in the open or closed

position with a single key.

Customer Problem:

To interlock a single acting, pneumatic

actuator on a ball valve.

SFC Solution:

Where single acting, spring return

pneumatically actuated valves have to be

incorporated into an interlock sequence,

an interlocked 3-way isolating valve is a

simple and effective solution.

The isolating valve is located upstream of

the actuator control panel. When operating

Customer Problem:

To ensure two ports on an instrument

manifold can never be simultaneously

opened.

SFC Solution:

Needle valves of all types can be fitted

with SFC interlocks. Regardless of body

design, number of operating handles or

method of operation, SFC can supply a

solution to your problem.

In this illustration a 4-port instrument

manifold is equipped with SFC's NVL

Specials

PRODUCTS

Pneumatic Control Valves

Customer Problem:

To interlock a double acting, pneumatic actuator on a ball valve.

SFC Solution:

For this requirement SFC adapted their QLA interlock to incorporate

a sliding control lever with forward and backwards motion.

This linear motion interfaced with the pneumatic valve operating

lever to provide double acting operation.

the isolating valve, air pressure to the

actuator is vented to atmosphere, thus

completely disabling the valve.

Single or double key arrangements

can be used to isolate the valve in

any position.

In the illustration the interlock

incorporates a chassis plate for local wall

mounting, and a proximity sensor for status

indication back to a control room.

This arrangement is a cost effective add-

on control feature to all types of pneumatic,

hydraulic or gas actuators.

interlock. The locking device ensures

that pairs of operating handles can

only be operated one at a time.

Upon opening the first port,

the key becomes trapped.

The second port cannot be

opened until such time that the first

port has been closed, thus releasing

the operating key.

The opposite pair of ports are

controlled in the same way with a differently

coded key.

3-way isolating Valve C/W Proximity Sensor

Needle Valve Locks

Explosion Proof Interlocked Switch

18

Specials

PRODUCTS

Customer Problem:

To ensure that a dangerous rotating

hazard was secured against access which

could result in serious injury.

Further, power isolation alone was not

enough because the rotating hazard had a

run down period in excess of 3 minutes.

Customer Problem:

To mechanically interlock an electrically

operated device, within a hazardous

environment.

SFC Solution:

Where mechanical (interlocked) control

of powered equipment is required in a

hazardous area, the SFC switch lock

provides the perfect solution.

Customer Problem:

To permit complex variations in

operating sequences on pig

launcher/receiver systems.

SFC Solution:

The simplest interlock systems will

normally feature a 'linear sequence'. This is

where the outward 'journey' (operating

steps) are mirrored by the return journey.

However, from time to time non-linear

sequences are necessary. A typical

SFC Solution:

An SFC timer controlled interlock is

interfaced with a closure door interlock

providing access to the hazard. Upon

pressing the isolating switch, the timer

commences (varying run-down times can

be programmed). Only when the

programmed period of time has elapsed

can the key be removed, which in turn, is

used to unlock and open the access door.

In this illustration our 'QL' quarter turn

interlock is fitted to the actuator lever of an

Eexd IIb T6 hazardous area control

switch.

A single or dual key configuration can be

supplied to lock in the ‘ON’, ‘OFF’ or both

positions.

Switches of all zone protection

specifications can be provided.

example of a non-linear sequence is a pig

receiving procedure where double block

and bleed valves control complex nitrogen

purging, pressure equalisation, venting

and draining.

The sequence control unit is a

mechanical key issuing device. It is

normally placed locally to the valve

system. It differs from a key exchange unit

in that, upon inserting a permit key, a

selector knob is rotated to a fixed position

before the next key is issued.

Timer Controlled Interlock

Sequence Control Unit

19

Where security lock-off devices are required to provide mechanical locking of manual operators, SFC offer a fullcomplement of security and commissioning tools.

If sequential control is unnecessary but a secure lock is required, the SFC range of security products canprovide the solution you need.

ChainlokThe Chainlok is a unique device which

combines the features of padlocks and

interlocks.

A durable body and chain made from

316 Stainless Steel makes it suitable for

use in the most hostile environments.

Chainlok comes with 0.5m chain as

Security Products

PRODUCTS

ISO-LOKA multi-clasp, when used in conjunction

with SFC padlocks enable individual

personnel to isolate equipment while they

carry out their work, safe in the knowledge

standard (longer lengths available on

request).

Flag style ‘colour aware key’ enables

incorporation into interlock (key exchange)

systems.

Flip caps prevent ingress of foreign

matter when key is removed.

that the equipment cannot be re-energised

until all padlocks have been removed from

the clasp.

Two body and cable sizes are

available, along with varying

lengths of cable. Cable breaking

strains are available to 1750kg.

Car SealFor ‘one time only’ securing of manual

operators, including valves, switches,

enclosures. A simple ‘break-away’ screw

secures the seal in place. Removal can only

be achieved by cutting the seal cable.

20

Pressure Protection

Whether onshore or offshore, maintenance procedures to Safety Relief Systems on live

plant cause concern in ensuring that an open path to relief is maintained at all times

during the work exercise.

Most modern piping arrangements include spare relief capacity enabling continuous

production while such maintenance

procedures are conducted on live plant -

eliminating the requirement to isolate and shut

down the process.

Twin or multiple safety relief valve systems

are usually fitted with isolation block valves

upstream and downstream of each safety relief

valve - it is essential to ensure that the block valves isolating the spare relief valve are

opened BEFORE the block valves of the workpiece relief valve are closed. This issue is a

more acute problem if the respective relief valves and isolating block valves are distant or

out of sight of each other.

Various API and ASME codes recognise this hazard and recommend the use of

interlocks to eliminate this possibility. API RP 520 (Pressure Relieving Systems for

Refinery Services - Part II : Section 4 - Isolation Valve

Requirements) and API RP 14E (Design and

Installation of Offshore Production Platform Piping

Systems - Para.5.8.b [2] - Relief Device Piping)

specifically recommend interlocks in this situation to

ensure that (over)pressure protection of the vessel is not

compromised. These recommendations are also in

accordance with the requirements of ASME - Section

VIII - Appendix M.

Fitting a valve interlock to the upstream and

downstream isolating valves on each safety relief valve

(PSV) will ensure these recommendations are

implemented.

An initiating key, issued from a secure location (Control

Room) commences the PSV changeover. Follow the Step

By Step procedures in the diagram.

....... ‘apart from the possibility of death or injury topersonnel, or pollution of the locality, what otherpossible impact could an over-pressure explosion orrupture of one of your main process vessels have onyour business’?

APPLICATIONS

Clive Lyme - Project Engineerhas been with SFC since1992 and is responsible forSFC business with associateGroup companies andagents/distrbutors in Europe.

Dave Selsby - Senior SiteEngineer has been with the

company since 1985 andheads a crew of 4 site

engineers responsible forinstallation and

commissioning of SFCsystems at client locations

worldwide.

21

• ILLUSTRATION STATUS:

PSV1 on line: PSV2 isolated

Block Valves V1, V2 & V4* are Locked Open (L.O.)

Block Valve V3 is Locked Closed (L.C.)

*Spare outlet (downstream) block valve normally L.O. especially if

lower pressure rated than corresponding inlet (upstream) block valve.

• REQUIREMENT:

There is always an open path to relief.

(Inlet block valves V2 & V3 must never be closed at the same time.)

• MAINTENANCE TASK:

To commission PSV2 into service.

To isolate and permit removal of PSV1 for testing/servicing.

• WORK SEQUENCE:

1. Key ‘D’ is issued from the Control Room to initiate the Permit to Work.

2. Key ‘D’ unlocks and enables the opening of spare inlet block valve V3.

Typical ‘4 Block Valve / 5 KeyInterlock System’

APPLICATIONS

3. V3 is operated to open and is L.O. by removing Key ‘C’.

PSV2 is now on line.

4. Key ‘C’ is transferred to unlock and close inlet block valve V2.

5. V2 is L.C. by removing Key ‘B’.

6. Key ‘B’ is transferred to unlock and close outlet block valve V1.

7. V1 is L.C. by removing Key ‘A’.

The return of Key ‘A’ to the Control Room closes-out the work

permit and enables the issue of instructions for removal of PSV1

for testing and servicing.

Twin PSV Changeover Sequence

It should be noted this interlock arrangement further ensures

that the higher pressure rated inlet block valve V2 is closed

before its corresponding lower pressure rated outlet block valve

(V1). Conversely, this key interlock arrangement would also

ensure opening of low pressure outlet block valves before

opening of high pressure inlet block valves.

KEYSA & BV1

KEYSE & DV4

KEYSB & CV2

KEYSD & CV3

PSV1

PSV2

22

Tankers

Transfer operations of cargo to or from

tankers involving bulk powder, liquid or

gaseous product (possibly flammable or

toxic) are prone to spillage unless some

positive safety arrangement is in place to

ensure the carrier unit cannot move away

before all transfer (loading) hoses are

disconnected.

Cargo transfer operations on road and

rail tankers employ the same basic

principles and commonly feature

barrier/gantry structures, hose couplings,

supply valve(s) and hose storage

facilities. For these applications SFC

provide a positive mechanical safety

system that interlocks the loading bay

barrier with the gantry unit. The barrier

cannot be raised (permitting drive-away)

until the gantry has also been raised - and

this cannot occur until the loading

arms/hoses have been

retracted/disconnected. The SFC safety

interlock system can also include the

vehicle ignition system to ensure total

disablement of the tractor unit until alI

hoses are disconnected and gantry and

barrier positions are cleared to permit

safe moving away. Indeed the US Federal

Pipeline Safety Regulations make specific

reference to this situation for LNG

facilities.

APPLICATIONS

.......‘imagine the mess if a road tanker loading milk drove awaywith the transfer hoses still connected.....imagine the bigger‘mess’ if the cargo was LPG or LNG!’.......

Loading / Discharging operations - Road, Rail or Sea

Simon Read - SalesManager Europehaving over 20 yearsinternationalexperience in designand installation ofmajor projects.

Once the loading arms are correctly

positioned a secondary trapped key is

released from the control panel which

enables energising of the actuated supply

valve which can be opened enabling

product transfer. The tanker cannot be

moved while the loading arm is in position

and the loading arm cannot be retracted

until the supply valve has been closed.The SFC safety system

ensures that only when the valve is closed can the trapped

(energising) key be released from the interlocked supply valve

control switch. This key is returned and inserted into the loading

arm control panel to enable retraction of the Ioading arm(s). When

alI related procedures are completed, the entire system is

disabled by removing the original initiating/permit key.

23

These positive mechanical and electro-

mechanical arrangements ensure total safety

by eliminating the possibility of error or

violation - every operation executed by

h u m a n i n t e r v e n t i o n i s mechanically

regulated. Software-based electronic

management systems are also commonly

applied to regulate these procedures but are

vulnerable to the extent they are n o t

s c r u t a b l e a n d m a y b e p r o n e t o

s o f t w a r e contamination/corruption or

system failure.

APPLICATIONS

Sea tanker cargo transfer operations usually involve a push-

button station in the jetty control room regulating the operation of

automated loading arms and the (actuated) supply line valve(s).

When the tanker is berthed and ready for cargo transfer, the

automated loading arms are energised and located into position

on the tanker by insertion of an initiating/permit key into the

loading arm control panel.

Tim Hughes - SalesManager UK has been

with SFC for over 10years having

progressed to hispresent position fromdesign draughtsman

and with extensive siteexperience.

24

Pig trap accidents involving operator

intervention can be prevented by SFC

coded-card key interlock systems.

DNV TN B 302 Technical Notes for

Fixed Offshore Installations describes

pig traps as 'primary grades sources of

hazard'. ASME and API codes equally

recognise pig trap hazards - especially in relation to the risk of

opening closures while the vessel remains under pressure. The

Pipelines Safety Regulations 1996 enacted into UK law in April

1996 requires operators of pipelines to provide safety systems

that ensure persons are protected from risk to their health and

safety - again describing the hazard of opening pig trap vessels

under pressure.

SFC interlocks can be specified to ensure the minimum safety

arrangement of interlocking the vessel vent valve with the pig trap

closure. This arrangement ensures (to the exclusion of all other

methods) the vessel VENT valve is OPEN before any attempt can

be made to open the closure.

.....“Imagine the consequences of opening a pig trap closurewith product in the barrel”

.....“Imagine the effect of attempting to pass a pig through apartially open outlet valve”

.....“Imagine getting a sniff of H2S ”

.....these things can happen - have happened!

Pig Traps

With interlocks fitted to both the vent

valve and pig trap closure, a key is

released when the vent valve is opened

- removing the key from the vent valve

locks the valve in the open position. This

key is coded in common with the closure

lock - only by opening and locking the

vent valve can the operator secure the correct key to proceed to

unlock and open the closure.

APPLICATIONS

(Bleed devices fitted into closure opening

mechanisms are alone an unreliable safety

arrangement to detect the presence of

residual product - they are prone to wax or

hydrates formations which can obstruct the

bleed channel inside the vessel thereby

misleading the operator to believe it is safe to

open the closure).

Ian McDonnell - BusinessDevelopment Manager hasre-joined SFC after a twoyear interval in valve sales.Ian was originally involvedat SFC in project sales andre-joined the company inJanuary 2000 to developnew markets.

Further procedure sequences can be regulated by interlocks to

include drain valves, nitrogen purge and water flush valves,

corrosion inhibitor and isotope functions, and indeed main

inlet/outlet and kicker valve functions - every system is designed

to meet clients' unique operating conditions/requirements.

Key interlocks can be integrated into pig trap control systems

even where the main inlet/outlet valves and kicker valve are

actuated (MOV's). In this situation, launching or receiving pigs is

a semi-automatic process with operator intervention limited to

push-button action either through a local control panel or effected

from a remote control station. Indeed, these valves may even be

programmed with ESD functions.

However, when it comes to loading or unloading of pigs, an

abnormal condition arises where software or electronic

interlocking arrangements between these valves are suspended

through the necessity to isolate these valves both from 'Remote'

and 'Local' settings to the 'Off' position. An SFC coded-card key

interlock system can be fitted to these valves to mechanically

prove their 'closed and isolated' status - releasing a key which

then enables operation of manually-operated valves related to

vent, drain, N2 purge and water flush procedures before enabling

any attempt to unlock and open the pig trap closure.

Only an SFC coded-card key interlock system can achieve the

condition of creating a positive link that makes the

operation/status of MOV's and manually-operated valves

completely interdependent and absolutely reliably ensures total

isolation, venting and draining of the vessel BEFORE any attempt

can be made to open the vessel closure!

APPLICATIONS

25

26

Fire Deluge Systems

APPLICATIONS

.......‘what's colourless, odourless, is all around us and can kill aperson in less than 2 minutes’ ?.......

International concern over the environmental effect of widespread use of CFC gases

has led to the phasing out of HALON (Halon 1301) as a fire extinguishing medium and its

substitution with Carbon Dioxide (CO2) or other inert gases.

CO2 is a very effective extinguishing agent and works by reducing oxygen levels to a

point where combustion cannot be sustained. It is a naturally occuring substance and

has no corrupting or polluting effect when released into the atmosphere - unlike HALON

which is a CFC compound.

Automatic CO2 fire extinguishing systems when activated are

designed to deluge an area within seconds. Typical installations

include turbine/generator enclosures, plenum chambers, computer

rooms, archives or any other enclosed area designated as being

not normally occupied. Such areas are occupied only on an

occasional basis usually for the purposes of inspection,

maintenance or repair.

CO2 is potentially fatal - anyone who may become

trapped in an enclosed space flooded with CO2

would very quickly suffocate.

Cliff Roberts - ProductionManager has been with thecompany since 1986 and isresponsible formanufacturing output timelyto clients’ delivery daterequirements.

27

APPLICATIONS

For the period in which work is being carried out

inside the enclosed space, the CO2 Supply is isolated

and the worker(s) cannot be locked in. However, to

ensure total worker safety each interlocked access

door within the system is fitted with a failsafe

emergency override escape mechanism which

permits a worker to strike a panic button or crash rail

that mechanically overrides the door latch mechanism.

Safe practice requires an arrangement which prevents casual or

unauthorised access into a (CO2) protected space and also

enables emergency exit at all times from the protected area. The

safety arrangements should also ensure that all doors and access

hatches remain locked during periods of normal operations and

that access to the protected area is controlled and authorised

only by the appointed authority.

SFC interlock systems can be applied for maximum effect to

permit access only under the strictest conditions. Access for

inspection or maintenance purposes is only possible by the issue

of an initiating 'permit key' by the appointed authority. This key

may be used to activate visual or audible alarms which denote

'work in progress' and / or the release of secondary key(s) which

enable isolation of the CO2 supply. Based on a key exchange

principle, further keys are released which enable unlocking of the

access door(s) and permit the entry of the worker(s) to undertake

the task at hand.

This safety solution from SFC fulfills the safety

requirements of NFPA12 * and BS 5306. #

* National Fire Protection Association (USA) - Carbon Dioxide

Extinguishing Systems - 1993 Edition.

# British Standard - Part 4 1986 - Specification for Carbon

Dioxide Systems.

Bryan Hughes - QualityManager has been with SFCsince 1992 and isresponsible for maintainingSFC’s accreditation to ISO9001.

Smith Flow Control Limited6 Waterside Business ParkEastways Industrial Estate

Witham, Essex CM8 3YQ, United KingdomTel. +44 (0)1376 517901 Fax. +44 (0)1376 518720

E-mail: sales@smithflowcontrol.comWeb: HTTP://www.smithflowcontrol.com