Technical Data for Couplings - KLINGER Mzansi

Technical Data for Couplings

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Technical Data

Introduction

Introduction

Overview

Angular Deflection

Setting Gap

Pressure Forces

Pipeline Design Extras

Installation

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- Glossary of Terms - Brief History of the Mechanical Coupling - Thomas Pipe Products Complete Range - Size - Working Pressure - Temperature - Suitability - Location - How it works

- Pipe Material - Pipe Outside Diameter - Diameter Measurement - Pipe Ovality - Pipe Tolerances - Pipe Coatings - Pipe Surface Finish - Working Pressure - Operating Temperature - Chemical Resistance - Corrosion, Site & Transport Protection - Spares

- Accommodation of Angular Deflection - Lateral Displacement - Ground Settlement - Long Radius Curves

- Pipe End Thrust & Pipe Restraint - Coupling Movement Under Pressure - Movement of Step Couplings due to Internal Pressure - Restrained Products - Restrained Adaptors & Dismantling Joints

- Anchored Couplings - Cathodic Protection - Center Registers - Inclined Pipelines - Shear Strength - Pipeline Expansion & Contraction - Pipe End Preparation

Glossary of TermsOD-Pipe Outside DiameterDN-Diameter Nominal = Nominal Diameter (ND) = Nominal Bore (NB)ID-Internal DiameterWP-Working Pressure = recommended operating pressureTP-Test Pressure. Traditionally 1.5 x WP for couplingsPN-Pressure Nominal = Nominal Pressure usually stated in bar. 1 bar = 0.1 MPa = 100 kPa = 100kN/m2PCD-Pitch Circle Diameter or Bolt Circle DiameteruPVC-Unplasticised Polyvinyl Chloride (Pipe)mPVC-Modified PolyVinyl Chloride (Pipe)oPVC-Orientated Polyvinyl Chloride (Pipe)HDPE-High Density Polyethylene PE100 (Pipe)MDPE-Medium Density Polyethylene PE80 (Pipe)LDPE-Low Density Polyethylene (Pipe)DI-Ductile Iron (Pipe)CI-Cast Iron (Pipe)GRP-Glass Reinforced Polyester (Pipe)GRE-Glass Reinforced Epoxy (Pipe)AC-Asbestos Cement (Pipe)FC-Fiberglass Cement (Pipe)EPDM-Ethylene Propylene Diene MonomerNBR-Nitrile Butadiene RubberVITON-Fluoroelastomer RubberDedicated Coupling-Suitable to fit on a single specified pipe ODWide Range/Wide Tolerance Coupling-Couplings with a wide working tolerance up to 23mmCOD-Constant Outside DiameterCID-Constant Inside DiameterMachined Pipe End-Certain pipe materials exhibit a machined end to provide a uniform specified diameter pipe end to connect the pipes, such as AC pipe.Pipe Barrel-The barrel of a pipe is the section between the two prepared pipe ends.FBE-Fusion Bonded Epoxy corrosion protection coatingISO-International Standards Organization

NoticeEvery effort has been made to ensure that the information contained in this document is accurate at the time of publishing. KLINGER Pipe Products assumes no responsibility or liability for typographical errors or omissions or for any misinterpretation of the information within the document and reserves the right to change without notice. All information provided is intended as a guideline for the use of products manufactured and distributed by KLINGER Pipe Products. Good engineering practice should always prevail and performance limits of the products should never be exceeded. No part of this documentation may be reproduced, in any form or by any means, electronic, hard copy or otherwise, without prior written permission of KLINGER Pipe Products.

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Introduction

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How it WorksMost mechanical slip-on compression couplings operate on the same principle. The basic coupling configuration consists of a set of bolts with nuts and washers (1), two end rings (2), a center sleeve (3) and two tapered elastomeric rubber gaskets (4). The center sleeve is located between the rubber gaskets which are in turn housed inside the end rings.

1. Captivated ‘D’ Cup Bolt2. End Ring3. Center Sleeve or Center Barrel4. Tapered Rubber Gaskets

The operation of a mechanical coupling is simple. Thomas mechanical compression couplings use only three nut sizes - therefore only three size spanners are required to assemble all standard couplings: - 19mm Spanner for M12 Bolts and Nuts - 22mm Spanner for M14 Bolts and Nuts - 24mm Spanner for M16 Bolts and Nuts.

Once aligned correctly, the coupling is ready for tightening. When the nuts are tightened (1) the two end rings are pulled toward each other. Note the bolts have a captivated head, i.e. the ‘D’ cup mushroom head bolt locates into a ‘D’ shaped hole in the end ring, this locks the head of the bolt so that it does not spin when the nuts are tightened. The benefit of a captivated bolt head is that the installer does not need to use two spanners - as with an ordinary hex bolt head where a spanner is needed to hold the head of the bolt and another to turn the nut.

When the end rings are pulled toward each other the rubber is compressed in to the gap between the coupling sleeve (2) and the end ring resulting in a downward force on the pipe (3). The more the bolts are tightened the greater the compression force exerted on the rubber. At the specified torque ratings the coupling will provide a leak proof connection between two pipe ends.

Technical Data


Brief History of the mechanical CouplingThe first mechanical coupling was claimed by an American company named Dresser around the 1850's. With patent rights expiring after 20 years several new manufacturers began launching their own form of the mechanical coupling. In recent times the most notable is Viking Johnson from England who launched their first products in 1931.

Over the years Viking Johnson became leaders in the European pipe connection market. Being a colony of Great Britain, the South African market was exposed to the Viking Johnson (VJ) successfully marketed the VJ brand name to the extent that it has become generic.

In 1992, Viking Johnson withdrew manufacturing from South Africa. The saw the launch of Klamflex Pipe Couplings.

1999 saw the founding of another South African coupling manufacturer named Aqualok. Over a period of 7 years the Aqualok product was successfully integrated into the Southern African pipe connection market.

2007 saw the launch of Thomas Pipe Products as designers, manufacturers and distributors of pipe connection and repair products, including mechanical couplings. In October 2011, Thomas Pipe Products purchased Aqualok, uniting the companies under the single brand name Thomas. The Thomas Pipe Products range offers a complete and economic solution for almost all pipeline connection and repair requirements. In June 2020 Thomas Pipe Products was sold to KLINGER South Africa (Pty) Ltd and is now known in the market as KLINGER Pipe Products since 1 July 2020.

KLINGER Pipe Products Complete RangeFrom DN15mm to DN3000mm.

Working PressureUp to 64 bar. Dependant on the size and product.

Temperature-40°C to 90°C (-40°F to 125°F) with standard EPDM rubber seals.

SuitabilityWater, air, sewage, marine applications, gas, oil and suspended solids. Subject to the products used and gasket material selected.

LocationAbove or below ground, in shade or direct sunlight. In factories, treatment plants and even marine structures & ships.

Overview

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Constant Inside Diameter pipe or CID pipes have a constant inside diameter along the entire length of the pipe. However, the outside diameter can vary. These pipes often exhibit a machined end (1) that has a smaller diameter to the central barrel (2) of the pipe length. For example a DN350mm Class 18 AC pipe has a machined end of 396mm. The barrel of the pipe bulges outward as much as 5mm bigger in diameter than the machined end = 401mm. With CID pipes it is important to know the OD of the barrel of the pipe to ensure the use of a wide range Unifit coupling that can accommodate both the machined end and the larger diameter barrel. A dedicated coupling is unable to accommodate the machined end and the barrel of these pipes.

Pipe OvalityGenerally pipe ovality should fall within 0.75% of the specified pipe outside diameter. However on large diameter pipes even this can become a large amount of ovality. Wide range Unifit couplings accommodate ovality easier than dedicated couplings due to the thicker rubber seal and wider operating tolerance of the product. Often selective bolt tightening is used to provide a uniform gap between pipe and coupling. More severe pipe ovality, up to 1% of diameter, can be rectified by ‘jacking’ the pipe. Care should be taken not to damage the corrosion protection coating.

When considering connections where ovality is known it is wiser to consult our offices to recommend alternative products such as our G-Flex Install couplings that can accommodate larger amounts of ovality.

Pipe TolerancesAll couplings provide optimum performance when it is a tight fit on the pipe. Wide range Unifit products will similarly have higher working pressures at the top end of the working tolerance than at the bottom. Many wide range couplings offer a working tolerance that overlaps either the next size above or below. It is therefore prudent to select the wide range coupling where the pipe fits in toward the top end of the working tolerance.

Example, when joining a 315mm OD PVC pipe there are two standard stock Unifit couplings available:1. TC0300 (302-318mm) - Top of range on 315 PVC2. TC0300-2 (315-332mm) - Bottom of the range. Although both will work at 16bar working pressure, the TC0300 offers a far higher working pressure on 315mm OD PVC pipe.

Technical Data

Pipe MaterialAll popular rigid pipe materials can be joined with a product from the KLINGER Pipe Products range. Most commonly used are the mechanical Unifit and Large Diameter Coupling products suitable for, but not limited to the following pipe materials: steel, stainless steel, ductile iron, PVC, HDPE, Glass Reinforced Polyester (GRP), concrete, clay and Asbestos Cement (AC).

The rigid materials with high strength characteristics such as steel, stainless steel and ductile iron can be joined using our standard fitting instructions. Lower strength more pliable pipe materials may require a reduction in bolt torque rating or a different product from our range.

GRP pipe can be damaged by excessive compression forces exerted on the pipe wall, longer coupling barrels to connect further from the pipe end and reduced bolt torque values are recommended. We generally recommend our G-Flex coupling with built in self-energizing rubber seal for GRP pipe as it offers negligible downward compression force on the pipe wall.

HDPE & oPVC pipe have a tendency to be effected by creep, expansion and contraction, due to thermal and pressure fluctuations. We offer a vast range of restrained and non-restrained coupling products for joining HDPE and oPVC pipe. Long barrel couplings are offered in order to take up any initial pipe movement experienced when an HDPE / oPVC pipeline is layed, buried and commissioned. If continuous expansion and contraction is experienced, an expansion bellows should be installed.

Please contact our technical sales staff to ensure the selection of the correct product for your application.

Pipe Outside DiameterWe manufacture products that can be specified to match pipe outside diameters from DN15mm to DN3000mm. Special products can be manufactured for non-standard pipe diameters. With the exception of our Internal Test Plug, all our products connect on the pipe outside diameter (OD). It is therefore imperative that the correct pipe OD is specified at the time of quotation and order.

Diameter MeasurementExperience has taught us that the most accurate method of measuring a pipe outside diameter is with the use of a Diameter Tape. Diameter Tapes wrap around the circumference of the pipe, thus eliminating the effects of ovality. Diameter tapes are available for purchase from our sales offices.


Overview

Technical Data


Pipe CoatingsMost pipes are finished with a corrosion protection coating. This coating effectively increases the OD of the pipe. Care should be taken to cater for the additional coating thickness. Certain coatings can add as much as 6mm to the pipe outside diameter, this can result in the manufactured coupling not fitting over the coated pipe end. Our sales offices must be informed at quotation stage to ensure the coupling can be sized to accommodate the increased pipe OD. Thick pipe corrosion protection wrappings must be removed from the pipe ends where a mechanical coupling is destined to be installed, generally referred to as a ‘cut back’ , the end of the pipe must be prepared so that the coupling can seat on a thinner corrosion protection film.

Pipe Surface FinishPrior mention is made of pipe end preparation referring to the distance back from the end of the pipe that must be prepared to enable an effective coupling seal. The pipe surface is to be round, smooth, clean, free of grooves, weld beads, bumps, score marks or other irregularities. In order to maintain specified coupling pressure ratings, pipe end tolerance should be within ± 0.75% of pipe outside diameter.

It must be noted that the preparation of pipe ends is to ensure the coupling seal performs optimally on the pipe end. There are limits to the performance of all engineering designs; in the case of mechanical couplings there are also limits in terms of the operating range of the product for pipe outside diameter, pressure rating and conveyance fluid chemical composition. The list can go on and on taking note of temperature, incline etc. With regard to the pipe end preparation it is always good engineering practice to ensure that the pipe is clean, round and free of grooves and weld beads. Rule of thumb is that the pipe end preparation should equal the total length of the product. Refer to dimensional details.

Working PressureThis is constrained by the coupling size and construction. Dedicated couplings or wide range Unifit couplings sealing at the top of their working tolerance will exhibit a higher working pressure. The test pressure of a mechanical coupling is 1.5 x the working pressure. Flanged products exhibit a working pressure determined by the flange rating. For example a Pn16 flange will have a 16 Bar working pressure and 24 Bar test pressure.

Special high pressure couplings can be manufactured for high pressure applications. Working pressures of 64 Bar are available. We have previously manufactured Large Diameter DN1600mm couplings with working pressures of 56 Bar.

Operating TemperatureOperating temperature of our products is determined by the rubber gasket material and corrosion protection coatings applied. Standard Unifit and Large Diameter couplings and flange adaptors are supplied with fusion bonded epoxy corrosion protection and EPDM rubber seals. These items are good for a working temperature up to 90°C. Special coatings and rubber seal compounds can be specified at quotation stage in order to manipulate the operating temperature of the product.

Couplings and flange adaptors exhibit their best performance character ist ics under constant temperature conditions. Elevated and continuous temperature fluctuations may result in the need for the coupling bolts to be regularly re-tightened. For this reason mechanical couplings are not recommended for pipe jointing in heating systems.

Chemical ResistanceAs with temperature performance the chemical performance of a coupling product is determined by the suitability of the corrosion protection coating and rubber compound. It is necessary for the customer to ensure that our standards products, which are fusion bonded epoxy coated and supplied with EPDM rubber seals, are suitable for contact with the pipeline content.

Various alternative coatings are available on request. Similarly special rubber compounds can be supplied. The entire metallic material of construction can also be altered to Stainless Steel Grade 304 , 316, or 904L if necessary.

Corrosion, Site & Transport ProtectionAll standard KLINGER coupling products are coated with fusion boded epoxy to SABS 1217. Rilsan Nylon 11 or hot dip galvanizing is available on request. Bolts and nuts are coated with hot dip galvanizing or superseal electro galvanizing. KLINGER products are dispatched well equipped to withstand transport, storage, site and corrosion damage. Each item is individually shrink wrapped with a 150 micron protective plastic shrink wrap and all exposed bolt ends are supplied with plastic thread protection caps to prevent damage to the threaded bolt end.

SparesAll manufactured components are available as spares on short notice.

Angular Deflection

COUPLING DEFLECTION INCLINATION

DN (degree)

(mm)

Up to DN450 ± 6° 1 in 10

Over DN450 - DN600 ± 5° 1 in 12

Over DN600 - DN700 ± 4° 1 in 15

Over DN700 - DN1200 ± 3° 1 in 20

Over DN1200 - DN1800 ± 2° 1 in 30

Over DN1800 ± 1° 1 in 60

FLANGE ADAPTOR DEFLECTION INCLINATION

DN (degree)

(mm)

Up to DN450 ± 3° 1 in 20

Over DN450 - DN600 ± 2.5° 1 in 24

Over DN600 - DN700 ± 2° 1 in 30

Over DN700 - DN1200 ± 1.5° 1 in 40

Over DN1200 - DN1800 ± 1° 1 in 60

Over DN1800 ± 0.5° 1 in 120

COUPLING MINIMUM SPOOL

DN PIPE LENGTH L

(mm) (mm)

Up to DN450 Displacemnet Y x 10

Over DN450 - DN600 Displacemnet Y x 12




Over DN1800 Displacemnet Y x 60

SPOOL PIPE LENGTH

Technical Data


Accommodation of Angular DeflectionCouplings and Flange Adaptors allow for angular deflection during installation. This angular deflection may take place during operation due to various reasons such as ground settlement. However, mechanical couplings are not rubber bellows and should therefore not be used as such. If the angular deflection occurs continuously a mechanical coupling is not suitable. The ability of a Unifit or Large Diameter coupling to accommodate angular deflection enables it to be used in several ways:- To take up minor misalignment or lateral displacement- To accommodate ground settlement- To lay pipes in long radius curves.

The table below lists the maximum allowable angular deflection of Unifit and Large Diameter Couplings and Flange Adaptors.

X

The allowable angular deflection of a flange adaptor, half coupling or end cap, is half that of a similar sized coupling. This is because a coupling has 2 rubber seals to accommodate pipe angularity, whereas a flange adaptor, half coupling or end cap has only a single rubber seal.

The previous table represents the maximum angular deflection for each nominal size range and should only be used when the pipes will not move in service. For conditions where ground settlement or movement is possible, it is recommended to halve these figures to allow for in-service flexibility.

Lateral DisplacementIt is good engineering practice to align pipes correctly before joining them with a mechanical coupling. Couplings can accommodate a small degree of pipe end misalignment.

Lateral displacement cannot be accommodated by a single coupling. Lateral displacement (Y) between two pipe ends is rectified by using two couplings and a spool pipe of appropriate length (L) set at the correct angle (X). The length of the spool pipe should be calculated to ensure that the coupling does not exceed its maximum allowable angular deflection (refer to previous table).

The minimum length (L) of the spool pipe can be calculated using the table below:

Example: Pipe OD = 508mm.Lateral displacement to be accommodated = 120mm.Minimum spool pipe length L = 120 x 12 = 1440mm.For Flange Adaptors these lengths must be doubled.

Angular Deflection

PIPE MAXIMUM

DN ANGULAR

(mm) DEFLECTION 3m 6m 9m 12m

Up to DN450 6° 29m 57m 86m 115m

Over DN450 - DN600 5° 34m 69m 103m 138m

Over DN600 - DN700 4° 43m 86m 129m 172m

Over DN700 - DN1200 3° 57m 115m 172m 229m

Over DN1200 - DN1800 2° 86m 172m 258m 344m

Over DN1800 1° 172m 344m 516m 688m

PIPE LENGTH

L

MINIMUM CURVE RADIUS

Technical Data

Ground SettlementWhere a pipe an underground structure, ground settlement may occur. This can be accommodated using two step couplings with a short spool pipe. In this case, pipe trenches are excavated below the pipe invert to allow for pipe bedding. If this is bedding is to be flexible (e.g. granular fill), some settlement will inevitably occur when the trench is backfilled. To minimize bending stresses in the pipe exiting the structure, a coupling should be installed as close as possible to the structure. The two couplings together allow the spool pipe to angulate (X) taking up the ground settlement (Y). The minimum length of spool pipe (L) is determined using the Spool Pipe Length table on the previous page. The structural strength of the pipe in bending may be considered.

Long Radius CurvesCouplings can be used to enable pipelines to be laid in long radius curves to follow geographic contours or avoid obstacles. This can be done without the use of specialized high cost bends and the associated necessary thrust blocks.

With reference to the figure above and using the equation below the radius of the curve can be calculated.

Radius R = L 2 sin ½ X

Where: R = Radius of curve L = Pipe length X = Angular deflection


The table below provides the minimum curve radius when pipes are laid with couplings at their maximum allowable angular deflection. It is important to note that the table below does not allow for any in-service movement. It is good engineering practice to allow for settlement. Therefore in conditions where ground settlement or movement is possible, it is recommended to halve the angular deflection and hence double the minimum curve radius figures to allow for in- ervice flexibility.

In above ground pipelines the lateral thrust forces must be restrained by a bespoke pipe support or restraint system. The lateral thrust forces generated due to angular deflection within a coupling are generally supported by suitable trench bedding, backfill and compaction. In the image below DN750mm KLINGER couplings were used to follow the curve of the pipeline. The pipes were laid above ground and restrained using weld on restraining harnesses.

Setting Gap

DN PRODUCT MAXIMUM

(mm) SLEEVE COUPLINGS FLANGE GAP

LENGTH (mm) G

(mm) (mm) (mm)

≤ 200 100 16 10 32

225 - 600 160 25 20 50

> 600 - 900 200 25 20 50

> 900 200 40 30 75

Long barrel ≥ 300 Ø dependant Ø dependant Ø dependant

RECOMMENDED GAP

SETTING GAPS

Technical Data

InstallationNOTE:Follow Installation InstructionsDo not encase in concreteLeave couplings exposed for pressure testing.

Coating Hanging RingNOTE:Products may be supplied with a small ring welded to the sleeve in order to assist with hanging during the coating process, this is not a lifting eye for a complete product.


Setting GapMechanical couplings are used to join pipes and allow for a certain degree of flexibility. This flexibility is due to movement of the pipeline during its lifetime in service. Mechanical couplings are designed to accommodate this movement without leaks occuring. The movement of the pipeline will result in axial and angular displacement of the pipe ends within the couplings. Axial movement movement is generally attributed to thermal pipeline expansion and contraction. Angular deflection can occur due to ground settlement.

Under normal working conditions the ends of two pipes within a coupling should never come into contact with each other. In increasing temperatures the pipe lengths will expand. If pipe ends butt up against each other in service there exists a possibility for the pipe lengths to buckle. In decreasing temperatures the pipe lengths may contract and other risks exists. If the gap between the two pipe lengths is to large on installation, the pipe ends may pull out of the coupling, leading to failure if the pipeline.

Therefore, it is necessary to ensure that the specified setting gaps are maintained during installation. Numerous variables exist such as differing temperature ranges and coefficients of expansion and contraction. Similarly less rigid pipe materials such as oPVC may increase in diameter under pressure resulting in a ‘shortening’ of the pipe length. In this case long barrel coup l i ngs and m in imum se t t i ng gaps a re recommended.

The table below lists recommended setting gaps for KLINGER couplings & flange adaptors. This distance aims at ensuring the pipe ends do not butt up against each other under normal operating conditions when experiencing maximum allowable angular deflection. Similarly, a maximum setting gap is provided to ensure that the pipe ends do not pull out of a coupling when installed at the maximum allowable angular deflection.

Pressure Forces

Technical Data


Pressure Forces

Technical Data


Movement of Step Couplings due to internal pipeline pressure forces.If a Unifit Coupling is installed within the angular tolerance of 5-6° or less (pipe angular deflection up to DN600mm) then there is no reason for the coupling to move. However, step couplings are inclined to move due to the thrust of the internal pipeline pressure on the reduction of diameter across the step coupling. The step coupling will always move from the larger OD pipe to the smaller OD pipe, regardless of the direction of flow.

A simple measure to prevent the movement of step couplings is to manufacture a removable restraining strap. The strap bolts around the pipe diameter of the smaller pipe. When the step coupling begins to move it butts up against the restraining strap and is prevented from sliding further. This method has been utilised successfully by Durban Metro for more than 15 years when using step couplings to join from AC pipe to smaller OD PVC pipe.

Any step coupling will have an un-equal thrust load effectively pushing the coupling from the larger pipe onto the smaller pipe. For the above example of a step coupling from 508mm steel pipe to a 532mm ductile iron pipe, the thrust load can be calculated as follows:

P=F/ATherefore F=PA=Test Pressure x AreaF=2.5MPa x (Area larger end of step coupling-Area

2smaller end of step coupling)m2 2 =2500000Pa x ((3.1416/4)* 0.538m - 0512 m )

2 =2500000Pa x ((3.1416/4)* 0.0273m 2 =2500000Pa x 0.02144m

=53603.5N

1 N is equal to 0.101971621 kilogram.

Therefore F=5466kg=5.466 tonnes.This is a substantial axial thrust force exerted on the step coupling.

Pressure Forces

G-Flex Gripper

Restrained Products

Couplings & Flange Adaptors

EvoGrip

DN20-350mmCoupling products

63-315mmCouplings & Adaptors

110-160mmCoupling products

DN50-3000mmFlanged products

Technical Data


Restrained Products Buried pipelines are generally restrained bu correct bedding and backfill along with concrete trust blocks at bends, chambers and reducers. In above ground applications it may be necessary to restrain the pipe by other means, often accomplished by utilizing a fully restrained product. The KLINGER product offering includes a section of Restrained Couplings & Flange Adaptors.

Dism. Joint & Rest. FA

PolyGrip

Pressure Forces

Technical Data



Technical Data

Anchored CouplingsKLINGER Couplings can be supplied with an Anchoring Cradle that can be bolted to a concrete plinth, structure, bridge or base. The cradle supports the coupling center barrel / sleeve when carrying a full pipe span (up to 10m) filled with water.

An anchored coupling provides an alternative method of supporting pipes above ground. Pipelines must remain directly above the cradle and remain relatively horizontal. Anchored above ground pipelines reduce installation costs and pipe installation time.

Anchored couplings are able to withstand the thrust forces associated with the maximum allowable angular deflection of the coupling.

Anchored couplings are generally supplied with center registers to prevent pipe creep.

Anchored couplings are not designed to withstand the axial thrust forces associated with internal pipeline pressure or external pressure forces and should therefore generally not be used in conjunction with restraining harnesses.

NOTE:An engineering study should be conducted to ascertain the suitability of anchored couplings when used with restraining harnesses.

This is to ensure the anchor points of the cradle are not responsible for preventing pipe movement or restraining against internal pipeline pressure thrusts. The anchor points of a cradle are designed to support the pipeline vertically above ground level.

A suitable plinth design must be considered in order to support the pipe and the weight of a 10m length of pipe filled with water.

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1 - Cathodic connection stud on opposing pipe ends2 - Cathodic connection stud on coupling end rings 3 - Cathodic connection stud on coupling sleeve

1 - Coupling End Ring2 - Coupling Bolts3 - Chemical Anchor Bolts4 - Anchor Cradle5 - Plinth

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Cathodic ProtectionWhen specified, KLINGER couplings can be included in pipelines requiring cathodic protection. Electrical connections can be made to the coupling end ring and sleeve via cathodic protection pads or threaded studs.


Center registers are normally not necessary for buried couplings as the soil prevents coupling creep. However they may be necessary in wet clay or marshy soil conditions. Center registers may be useful in critical assembly conditions ensuring the correct location of the coupling over the pipe joint. They are not suitable for step couplings due to the internal thrust forces.

Center registers are available in electro-galvanized mild steel or stainless steel in the following sizes:

COUPLING PIN THREAD

DN DIAMETER

(mm) (mm) (mm)Up to 600 10 M12Above 600 14 M16

CENTER REGISTERS

Technical Data

Effects of External & Pipeline Vibration on a Mechanical CouplingExperience has taught us that extreme and regular vibration applied to a pipeline and / or the surrounding ground can result in the coupling bolts gradually working loose.

A case study in Kalk Bay, Cape Town, revealed that DN700mm M16 coupling bolts loosened rapidly with the regular passing of a train on a nearby railroad. Many couplings were backfilled, compacted and tarred beneath a roadway within 8m of a railroad. Each of these couplings were unearthed and re-torqued to prescribed levels on 3 occasions. Ultimately the solution lay in tightening the coupling bolts with the use of ‘LockTite’ and a ‘Nylock’ nut tightened behind the coupling nut. Therefore each bolt had two nuts tightened together with ‘LockTite’.

Torquing the nuts together, prevented any further loosening of couplings.

An additional case study in Limpopo Province South Africa revealed a very similar result. Several TC0150 couplings were installed on water lines feeding a Rock Crushing Plant Segregator on a Platinum mine. With extensive vibration the M12 coupling bolts repeatedly loosened over a period of several weeks. Two nuts were tightened on each coupling bolt with the use of ‘LockTite’ and the problem was resolved.

Center RegistersOwing to continuous pipe movement from pipeline operating vibrations, temperature expansion and contraction etc., couplings installed above ground tend to creep along the pipe. This is particularly evident on inclined pipelines. If left unchecked the coupling may creep off a pipe joint resulting in pipeline failure. The most economical means of preventing this is with a fixed or removable center register.

Fixed center registers are a series of pins welded on the internal center line of the coupling sleeve

Couplings with fixed center registers can not be slipped over a pipe end. Therefore, once installed, couplings with fixed center registers can not be slid back off a pipe joint allowing a single length of pipe to be removed from a pipeline.

A removable center register consists of a threaded pin that is tightened into a threaded hole in the center line of the coupling sleeve. The center register is inserted from the outside of the coupling. The pin extends through the coupling sleeve and interferes with the pipe wall. Therefore the center register must fit between the two pipe ends. Once a center register is removed, the coupling may be slid over the pipe end exposing the pipe joint. A single length of pipe can then be removed and replaced if necessary.



Technical Data


Inclined PipelinesIt is important to consider coupling creep on inclined pipelines. Owing to the effects of gravity and continuous pipe movement from pipeline operating vibrations, temperature expansion and contraction etc., couplings installed above ground tend to creep along the pipe. This is particularly evident on inclined pipelines. If left unchecked the coupling may creep off a pipe joint resulting in pipeline failure. Similarly it is important to anchor the pipe to prevent the pipe sliding down the slope.

Buried pipeline generally receive sufficient restraint from correct trench bedding, backfill and compaction to prevent pipe creep down slopes. However, gravity forces must always be considered in a proper engineering assessment of the pipeline design.

NOTE:Center registers are not suitable to restrain pipe weight, axial thrusts or pipeline thrusts, only to restrain the coupling itself. Pipes must be properly anchored.

Pipeline anchorage must be suitable to withstand the operating and gravitational forces exerted within and on the pipeline. This design is beyond the scope of this document.

It is our recommendation that both pipe ends entering a coupling are suitably anchored and restrained. Pipe alignment limits must be adhered to in order to prevent excessive shear loads being exerted on the coupling.

Anchored coupling using center registers should only be used on horizontal pipelines. If they are used on inclined pipelines the pipe lengths must be fully anchored and restrained.

Shear StrengthStandard KLINGER couplings are generally not capable of withstanding the shear forces associated with the weight of a 9.144m length of pipe full of water, when supported between two couplings. Therefore pipes between couplings should be adequately supported to prevent sagging and coupling twisting. However, couplings can be designed that are capable of this and are available on request.

Pipe Expansion & ContractionCouplings and flange adaptors provide a simple solution for problems arising from thermal expansion and contraction of pipeline components. By means of gasket deformation as apposed to a sliding action over the pipe surface, Unifit couplings can accommodate a significant amount of pipe movement. The gasket allows for up to 4.5mm of pipe movement per gasket.

This action is generally sufficient to remove the need for special expansion jointing products. Most expansion movements due to normal ambient temperature variants can be accommodated using mechanical couplings. Stepped couplings permit the same total expansion movement as straight couplings. However, pressure thrust may act on the stepped coupling causing the stepped coupling to move along the pipe with repeated expansion movement. Restraint for the coupling will be required.

Pipe End PreparationPipe end preparation refers to the distance back from the end of the pipe that must be prepared to enable an effective coupling seal. The pipe surface is to be round, smooth, clean, free of grooves, weld beads, bumps, score marks or other irregularities. In order to maintain specified coupling pressure ratings, pipe end tolerance should be within 0.75% of pipe outside diameter.±

It must be noted that the preparation of the pipe ends is to ensure the coupling seal performs optimally on the pipe. Limitations exist with the performance of all engineering designs; in the case of mechanical couplings there are limits in terms of the operating range of the product for pipe outside diameter, pressure rating and conveyance fluid chemical composition. The list can go on and on taking note of temperature, incline etc. Regarding pipe end preparation it is always good engineering practice to ensure the pipe is clean, round, and free of grooves and weld beads. Rule of thumb is that the pipe end preparation should equal the total length of the product. Refer to dimensional details.

PRODUCT PIPE MOVEMENT

(mm)

Coupling 10

Flange Adapter 5

End Cap 5

Half Coupling 5

EXPANSION & CONTRACTION

Installation

Technical Data

In this case there was no failure, however, it was recommended that an additional coupling be installed several meters from the flange adaptor to reduce the angular deflection to within the recommended limits.

A common installation error occurs when the installer tightens all the bolts on one side of the coupling first before tightening the bolts on the other. This is often found in trenches where the bolts on the top of the coupling are tightened and the bolts on the bottom of the coupling are not. This results in uneven rubber compression that can result in leaks. It is important to ensure the fitting instructions are followed, tightening bolts in a diametrically opposite manner, several turns at a time.

When couplings are correctly installed it is plain and clear to see the parallel end rings of the coupling. Similarly the amount of bolt thread protruding beyoud the nut on all the bolts is the same. Clearly indicating a correct tightening procedure was followed (see below).

Effects of poor installationExperience has taught us that the vast majority of mechanical coupling failures are due to poor installation. Similar to many mechanical products, if pipe couplings are not installed correctly, there exists an increased risk of failure.

It is imperative that the installer adhere to the performance limits of the coupling. Characteristics such as angular deflection, setting gap and lateral displacement are important performance limits that determine long term safe operation of a mechanical coupling. Performance limits are specified within this document and the relevant marketing material for each of our product ranges. Aside from the adherence to performance limits, adherence to fitting instructions is also important, and good engineering practice.

Coupling fitting instructions are available for download from our website:

www.klinger.co.za

Poor installation such as the uneven tightening of coupling bolts results in an uneven distribution of the compressive forces on the rubber seal. In extreme cases, the rubber seal may not extrude evenly between the pipe outer surface and the coupling centre barrel inner surface. Thus, resulting in a leak.

Under pressure, rubber behaves similar to a viscous fluid. It will move from a place of high compression toward a place of lower compression. Uneven bolt tightening creates uneven compression loads exerted within the rubber seal. The movement of the rubber is hence due to the uneven tightening of the coupling bolts. Once the rubber has moved, and the pipeline has settled, it is common to find that coupling bolts appear loosened. The nuts themselves have not loosened or moved, it is only that the opposing force of the rubber seal that has abated. When the coupling is loosened and re-tightened according to the correct installation procedure it is found that the coupling works as it should.

The 355mm PVC PN16 PVC pipe connection below shows an angular deflection of 6°. This is double the allowable angular deflection of 3° for a DN350mm Flange Adaptor.

6°

Parallel End Rings


Installation

Technical Data

KLINGER Pipe Products reduced thickness flanges only come into play from DN250mm and greater. As the flange pressure rating and the nominal diameter increases, so to does the variation between full thickness and reduced thickness flanges. It is prudent to check reduced flange thicknesses when ordering flange bolt sets.

Flange Bolting details for both full thickness and reduced thickness flanges are available from our sales office.

Flange Bolting vs. Flange ThicknessThere are many flange drilling specifications globally. Most countries have their own standardization bodies that control and issue standards to industry. Alternatively, standards from well established industrialized countries are used, such as British or American standards.

In Southern Africa the most common flange drilling specifications found in the civil pipeline and irrigation markets include the following:

- SANS 1123- BS 4504- EN 1092-1- BS 10- ANSI B16.5- ASME B16.47

It is common practice globally, among Flange Adaptor manufacturers to utilize reduced thickness flanges. This is due to the fact that a flange adaptor is a flexible joint with a rubber seal that does not carry the axial load of a pipe length.

Therefore consideration must be given when ordering flange bolt sets to cater for reduced thickness flanges present on most flange adaptors, restrained flange adaptors and dismantling joints. KLINGER Pipe Products reduced flange thicknesses are available for reference on our website and from our sales office.

The correct bolt length is important when bolting two mating flanges together. Industry ‘Rule of Thumb’ is to allow for 3 x Bolt Threads to be visible protruding from the fastened nut.

It is a simple process to calculate the correct bolt length with all the information at hand. Correct engineering practice is to use two washers, i.e. a washer beneath the bolt head and another beneath the nut.

Figure 1 shows two full thickness flanges of the same drilling pattern bolted together. The bolt length is sufficient to cater for the two flanges, the flange gasket, 2 x washers, a single nut and 3 x bolt threads protruding through the nut.

Figure 2 shows a single full thickness flange and a reduced thickness flange adaptor of the same drilling pattern bolted together. The bolt length is sufficient to cater for the two flanges, the flange gasket, 2 x washers, a single nut and 3 x bolt threads protruding through the nut. However, because the reduced thickness flange is thinner than a full thickness flange the bolt length can and should be shortened.

Figure 1.

Figure 2.

WWW.KLINGER.CO.ZA

[email protected] TEL: +27 11 794 7594

CAPE TOWN TEL: +27 21 511 1337

Every effort has been made to ensure that the information contained in this document is accurate at the time of publishing. KLINGER Pipe Products assumes no responsibility or liability for typographical errors or omissions for any misinterpretation of the information within the document and reserves the right to change without notice.

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Date post:	13-Nov-2021
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Technical Data for Couplings - KLINGER Mzansi

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