PETRONAS TECHNICAL STANDARDSDESIGN AND ENGINEERING PRACTICE MANUAL ON-LINE PROCESS STREAM A NAL YSIS - SAMPL E TAK E- OFF &TRANSPORTATION PTS 32.31.50.10 DECEMBER 20072010 PETROLIAM NASIONAL BERHAD (PETRONAS) All rights reserved. No part of this document may be reproduc ed, stored in a retrieval system or transmitted in any form or by any means (electron ic, mechanical, photocopying, recording or otherwise) without the permission of the copyright owner
PETRONAS Technical Standards (PTS) publications reflect the views, at the time of publication,of PETRONAS OPUs/Divisions.
They are based on the experience acquired during the involvement with the design, construction,operation and maintenance of processing units and facilities. Where appropriate they are basedon, or reference is made to, national and international standards and codes of practice.
The objective is to set the recommended standard for good technical practice to be applied byPETRONAS' OPUs in oil and gas production facilities, refineries, gas processing plants, chemical
plants, marketing facilities or any other such facility, and thereby to achieve maximum technicaland economic benefit from standardisation.
The information set forth in these publications is provided to users for their consideration anddecision to implement. This is of particular importance where PTS may not cover everyrequirement or diversity of condition at each locality. The system of PTS is expected to besufficiently flexible to allow individual operating units to adapt the information set forth in PTS totheir own environment and requirements.
When Contractors or Manufacturers/Suppliers use PTS they shall be solely responsible for thequality of work and the attainment of the required design and engineering standards. Inparticular, for those requirements not specifically covered, the Principal will expect them to followthose design and engineering practices which will achieve the same level of integrity as reflectedin the PTS. If in doubt, the Contractor or Manufacturer/Supplier shall, without detracting from hisown responsibility, consult the Principal or its technical advisor.
The right to use PTS rests with three categories of users :
1) PETRONAS and its affiliates.
2) Other parties who are authorised to use PTS subject to appropriate contractual
This PTS specifies requirements and gives recommendations for the design andconstruction of systems for sample take-off and transport of the sample to on-line processstream analysers. This PTS is a revision of the PTS of the same title and number datedOctober 1995.
This PTS is one of a series of on-line process stream analysis PTSs. The other publications
are:
PTS 32.31.50.11 Sample conditioning
PTS 32.31.50.12 Analysers
PTS 32.31.50.13 Analyser Houses
1.2 DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS
Unless otherwise authorised by PETRONAS, the distribution of this PTS is confined tocompanies forming part of PETRONAS or managed by a Group company, and to
Contractors nominated by them.
This PTS is intended for use in oil refineries, chemical plants, gas plants,exploration/production and supply/marketing installations. When PTSs are applied, aManagement of Change (MOC) process should be implemented. This is of particularimportance when existing facilities are to be modified.
If national and/or local regulations exist in which some of the requirements may be morestringent than in this PTS the Contractor shall determine by careful scrutiny which of therequirements are the more stringent and which combination of requirements will be
Fast loop Refers to a sample transport system that takes a sample
from the process at one point and returns the withdrawnsample back to the process at another point.
LNG Liquified Natural Gas
PEFS Process Engineering Flow Scheme.
Piping class An assembly of piping components, suitable for a definedservice and design limits, in a piping system. Piping classesfor refining and chemicals are contained in
PTS 31.38.01.12; piping classes for exploration andproduction are contained in PTS 31.38.01.15
Process line The piping used for transport of fluids (other than samplelines).
Sample A representative portion of the product or process streamhaving all relevant properties of the product or the processstream itself.
Sample conditioningsystem One or more devices that properly prepare a portion of thesample from the sample transport system for testing by theprocess analyser to meet the requirements of the analyser.
Sample line The tube or pipe used for transporting the sample.
Sample pre-conditioningsystem
Consists of one or more devices that condition the sample(pressure, temperature, flow, change of state) so that it issuitable to be transported to the sample conditioningsystem. The sample pre-conditioning system forms part of
Secondary loop A circulating loop, part of the sample transport system,
which is fitted to reduce the lag time caused by componentssuch as filters, coalescers, etc., and/or to reduce thequantity of a sample entering the analyser house. Thesecondary loop is part of the sampling conditioning system.
Single line sampletransport
Refers to a sample transport system that returns the wastesample to a utility system.
1.4 CROSS-REFERENCES
Where cross-references to other parts of this PTS are made, the referenced sectionnumber is shown in brackets. Other documents referenced by this PTS are listed in (7).
1.5 CHANGES FROM THE PREVIOUS EDITION
The previous edition of this PTS was dated October 1995. Other than editorial revisions,the following are the main changes to that edition:
Old section New Section Change
1.3.2 1.3.2 Changed definition of “Fast Loop”
2.1 2.1 Added requirements to tag and identify sampleconnections and to provide adequate straight lengths aftera flow disturbance.
2.3.2 2.3.2 Clarified a default choice of AISI 316 for wetted parts ofsampling system.
2.3.5 2.3.5 Added steam tracing of sample transport line.
2. INSTALLATION OF SAMPLE TAKE-OFF CONNECTIONS, SAMPLE PROBES AND
SAMPLE PRE-CONDITIONING SYSTEMS
2.1 LOCATION
The sampling point shall be selected at a point in the process such that:
• the handling of the equipment will not impair the safety of personnel or the plant;
• representative and timely information on the properties or composition of the processstream is obtained;
• it is optimised for accessibility and maintainability;
• lag times of the process are minimised, e.g., whether to sample upstream ordownstream of a process vessel, heat exchanger bank, etc.;
• temperature, pressure, or other conditions are as close as possible to the requiredspecification for the analyser.
Particular care should be taken to avoid locations where there is a possibility ofcontamination, or where pockets of gas/vapour/liquid or hydrocarbon/water/dirt may
accumulate in the process stream.In order to ensure representative sampling, samples should normally be taken from a pointwhere there is no possibility of a two-phase fluid.
Typically, good locations for sample take-off and sample return connections are thedischarge and the suction side respectively of pumps or compressors. The sample pointlocation shall be at a minimum of 2 pipe diameters downstream from any flow disturbance,e.g., a 90° bend in the pipe.
The sample take-off and sample return connections should be clearly identified and tagged
Both the process conditions and the nature of the fluid shall be taken into considerationwhen selecting materials.
Unless otherwise specified, AISI 316 stainless steel should be used for all wetted parts ofthe sampling system. Sample lines in piping shall be in accordance with the piping class.
The use of non-metallic materials requires the Principal's approval.
2.3.3 Sample take-off connections
Sample take-off connections shall be installed in accordance with the branch table of therelevant piping class.
Taking a sample from a vertical process line is the preferred method.
Sample take-off connections for gaseous products in horizontal process lines shall beinstalled on the top of the lines.
Sample take-off connections for liquid products in horizontal process lines shall be installedon the side of the process line.
2.3.4 Sample shut off valves
Process shut-off valves shall be in accordance with the piping class and should be ballvalves.
NOTE: Ball valves have a temperature limit; see the piping class.
2.3.5 Sample transport lines
If the viscosity of the sample is higher than 1 Pa.s at 30 °C, e.g. long residue, the size of
The flushing medium inlet connection shall be immediately downstream of the sample
take-off point. Block and bleed valves shall be provided if there is a risk of contamination ofthe process medium.
2.3.7 Sample pre-conditioning system
A booster device shall be installed if insufficient process pressure is available, or if thesample viscosity is too high to achieve the lag times specified in the analyser data sheet.Booster selection is a matter of economics and the booster could typically be a pump,compressor, eductor, etc.
2.3.8 Cooling and heating
Cooling shall be applied to the sample take-off point, the pre-conditioning system and thesample transport lines if at these points evaporation of the liquid sample may occur atmaximum specified ambient conditions. Furthermore, cooling may be applied:
• to improve the separation of liquids by coalescence;
• to control the sample temperature as specified for the analyser or sample conditioningsystem.
Cooling should be applied either by tap water or chilled water from a closed loop system.
Heat tracing by steam, hot water or electricity shall be applied to the sample take-off point,the pre-conditioning system and the sample transportation lines, if at these points freezingor solidification of a liquid sample or condensation of a gaseous sample may occur atminimum specified ambient conditions. The sample temperature should be at least 10 °Chigher than the highest possible dew point of the sample. Furthermore, heating may beapplied:
Sample take-off connections and/or sample pre-conditioning systems shall be installed sothat they are readily accessible from grade or from permanent platforms.
If a booster pump is required, it shall be installed at ground level on a concrete foundation.
Insulation of sampling components shall be in accordance with PTS 30.46.00.31
2.5 ELECTRICAL ASPECTS
PTS 33.64.10.10 shall apply.
Pumps and compressors shall have a local isolating switch, shall have adequate lightingand shall be provided with weather protection as required for that type of pump orcompressor.
Electrical apparatus for use in gas hazardous areas shall have a type of protection asdefined in IEC 60079-14. Installation shall be in compliance with local regulations.
If heating is needed, the components should be installed in a heated box rather than the
individual components being heated and insulated. Where sample lines enter or leave theheated box, insulating grommets or similar shall be installed to avoid metal-to-metal contactwith the enclosure.
All components selected for a preconditioning system should be rated for the relevantprocess conditions. If it is impractical to install the pre-conditioning system with the properrating for the process conditions, a relief valve shall be installed downstream of thepressure-reducing valve in the pre-conditioning system.
The relief fluid should be returned to the process. If that is impractical, it shall be returned
either to the flare system or to the drain system.
3.3.3 Sample pre-conditioning system components
3.3.3.1 General
Sample pre-conditioning systems shall be designed so that their components are readilyaccessible and can be removed with the minimum of disturbance to the system.
Sample pre-conditioning system components shall be shielded against the cooling effects
of wind, rain, snow, etc. In addition, the following shall apply:
3.3.3.2 For pressure reduction only:
Pressure reduction of gas and vapour samples shall be done as close as possible to thesample take-off point, with the secondary pressure as low as practicable. Pressurereduction reduces the hold-up time in the high-pressure part of the sampling system andthe low secondary pressure reduces the amount of material circulating in the samplingsystem, thus reducing the overall time-lag of the sample.
• condensation (and subsequent freezing) or the formation of hydrates may occur on
pressure reduction. The heat input shall at least compensate for the change in enthalpyupon pressure reduction.
3.3.3.5 A booster pump/compressor shall be used if either of the following conditions prevails:
• if the pressure at the sample take-off point is too low to create an acceptable lag time orif the sample might flash in the sample system, see (3.4.1);
• if the distance between the sample take-off point and the analyser location is too greatto obtain sufficient velocity in the sample transport line with the available differential
pressure.The pump capacity should not exceed 10 % of the minimum design flow for the relevantprocess line.
3.3.3.6 If rotameter-type flow indicators and flow regulating valves are installed:
• metal tube type shall be used for hazardous/toxic products,
• a glass tube may be used for other services if the pressure does not exceed 1 bar (ga)and/or the flow is less than 5 l/h.
3.3.3.7 Pressure indication
A pressure indicator shall be installed downstream of the pressure regulator. A pressureindicator should be installed upstream of the pressure regulator if no pressure indication isavailable within a distance of 5 m.
doubt, the choice of material shall be subject to consultation with the Principal. In addition,
heating (tracing) may be considered to avoid adsorption/desorption problems.The preferred type of tubing is seamless and in accordance with ASTM A 269 type 316. Incase of doubts about the corrosivity of conditions, internally or externally, the material mayhave to be upgraded in consultation with the Principal.
Sample transport lines for products in which traces of reactive compounds are to bemeasured, e.g., traces of hydrogen chloride, hydrogen sulphide, mercury, etc., shall betreated to minimise chemical reaction between the sample and the tube. These samplelines shall be cleaned during commissioning, e.g., with solvent or pickling solutions, in
accordance with the recommendations of the analyser Manufacturer.Pre-insulated or pre-traced tubing shall be used for sample lines that need heating and/orwinterization, unless its installation is impractical. The insulation material shall be inaccordance with PTS 30.46.00.31
3.4.3 Design of a single line sample transport system
A single line sample transport system shall be considered if a suitable return point in theprocess is not available. A balance shall be found between a short sample lag time and a
minimum amount of sample disposed of via the by-pass.For illustrations of single line sample transport systems, see (Appendix 3; Figures 3.1, 3.2, 3.3, and 3.4).
3.4.4 Design of a fast loop system
3.4.4.1 General
Sample conditioning systems form part of the fast loop. For details, refer to
Booster-driven fast loops shall be fitted in case of insufficient pressure. If the vapourpressure of the sample is close to the process line pressures, fast loop pumps shall beinstalled close enough to the process line to prevent cavitation at the suction end.
The fast loop pump/compressor shall have sufficient capacity to create the required lagtime. As an example:
Given:Sample transport line length: 150 mSample lag time shall be within: 30 s
Calculation:Linear speed in fast loop: 150 / 30 = 5 m/s minimum.
Once the pipe diameter is known, the required volume flow rate per second can now becalculated.
An addition of 50 % on the pump capacity should be applied.
3.4.4.5 Secondary loop
The driving pressure for a secondary loop shall be obtained from a restriction valve or aspring-loaded differential pressure valve in the sample conditioning system; seePTS 32.31.50.11
Waste samples and/or by-products from the process of analysis shall either be returned toa suitable point in the process (e.g. pump suction) or to a suitable utility system (e.g. theflare system, fuel gas system or the oil-contaminated drain system). The flare systemoption is preferred in such cases.
Details of the disposal of toxic waste samples are subject to the Principal's approval.
4.2 GASES
The handling of the gas samples may require intermediate processing by a samplerecovery system if insufficient pressure is available to return the waste sample to a suitableutility system.
Waste samples and/or by-products of the process of analysis shall not be discharged toatmosphere unless approved by the Principal. Exemptions are air and moderate amountsof hydrogen (e.g. column vent of a gas chromatograph), nitrogen, and other non-toxicand/or non-odorous compounds that are considered safe and non-hazardous for the
environment. Such discharges shall be directed into well-ventilated atmospheres.
4.3 LIQUIDS
Liquid samples and/or by-products of the analysis process shall be recovered by a liquidrecovery system for either recovery, if economic, or safe disposal. The preferred point ofdisposal is the oil contaminated drain system, provided that such disposal does not causeadverse operational and environmental conditions.
If specified by the Principal, sample transport lines shall be equipped with pneumaticallyoperated "spring to close/air to open" emergency shut-off ball valves. Fire safe ball valvesshall be used; see PTS 31.38.01.11
The pneumatic lines to the ball valves shall be plastic tubing over the last 2.5 m ofinstallation to facilitate automatic shutdown by melting of the tubing in case of a fire nearthe valves. The plastic shall be UV light resistant, i.e., black, polyethylene or polypropylenetubing or equivalent. Stainless steel tubing, equipped at strategic locations with fusibleplugs, should be considered in situations where the use of plastic tubing may result in
nuisance shutdowns due to chemicals weakening the plastic tubing.
The pneumatics shall be operated from an electrical solenoid valve. It shall be possible tooperate the solenoid valves remotely from a common contact in the Control Room and froman easily accessible common switch located on the outside wall of the primary entrance tothe Analyser House.
Factory inspection and testing of the probe shall be done in accordance withPTS 62.10.08.11
Field inspection and testing of the sample take-off and transport system, including pressuretesting, shall be done in accordance with PTS 62.10.08.11 unless the liquid or gas used forpressure testing would interfere with the intended measurement. For example, sampletransport lines for trace component analysis (moisture or other trace components) shall notbe pressure tested with liquids.
A full functional test shall be performed to verify that all sample emergency valves closeupon a command from the emergency shutdown system.
In this PTS reference is made to the following publications:
NOTES: 1. Unless specifically designated by date, the latest issue of each publication shall be used (togetherwith any amendments/supplements/revisions thereof).
PETRONAS STANDARDS
Index to PTS publications and standardspecifications
PTS 00.00.05.05
Thermal insulation (amendments/supplements to theCINI manual “Insulation for industries”) PTS 30.46.00.31
Piping - general requirements PTS 31.38.01.11
Piping classes – refining and chemicals PTS 31.38.01.12
Piping classes – exploration and production PTS 31.38.01.15
Protective steam heating of piping systems PTS 31.38.30.11
Instruments for measurement and control PTS 32.31.00.32
Online process stream analysis - sampleconditioning
PTS 32.31.50.11
Online process stream analysis - analysers PTS 32.31.50.12
Online process stream analysis - analyser houses PTS 32.31.50.13
Installation of on-line instruments PTS 32.37.10.11
