Ma’aden Engineering Manual Specificationmaeum.ipdisk.co.kr/publist/VOL1/maeumnet/data/Adobe PDF 로우데… · Ma’aden Engineering Manual Rev. Date: 12 Sept 2011 Specification

Ma’aden Engineering Manual Rev. Date: 12 Sept 2011 Specification Rev: C01

PROPRIETARY & Pressure Testing of Piping Page 2 of 21

CONFIDENTIAL Doc No: MD-101-SMEM-EG-PI-SPC-0007

Table of Contents 1. Introduction ............................................................................................................................................ 4

1.1 Scope ............................................................................................................................................. 4 1.2 Purpose .......................................................................................................................................... 4

2. Key Terms and Definitions ...................................................................................................................... 4

3. Referenced Documents ........................................................................................................................... 5

3.1 Statutory Regulations ...................................................................................................................... 5 3.2 Industry Codes and Standards ......................................................................................................... 5

3.2.1 International Codes and Standards ...................................................................................... 5 3.2.2 Alternative Design Codes .................................................................................................... 6

3.3 Ma’aden Standards ......................................................................................................................... 6

4. Materials ................................................................................................................................................. 6

5. Execution ................................................................................................................................................ 6

5.1 Quality ........................................................................................................................................... 6 5.2 Testing Requirements...................................................................................................................... 6

5.2.1 General ............................................................................................................................... 6 5.2.2 GRP Piping ......................................................................................................................... 7 5.2.3 Rubber Lined Piping ........................................................................................................... 7 5.2.4 Gravity Sewer ..................................................................................................................... 7 5.2.5 Vessels and Equipment ....................................................................................................... 8 5.2.6 Instrumentation ................................................................................................................... 8 5.2.7 Testing Methods and Pressure ............................................................................................. 8 5.2.8 Isolation of Instruments During Pressure Test ...................................................................... 8

5.3 Testing Medium .............................................................................................................................. 9 5.3.1 Water ............................................................................................................................... 9 5.3.2 Other Mediums ................................................................................................................... 9

6. Preparation for Test ................................................................................................................................ 9

6.1 Planning ......................................................................................................................................... 9 6.2 Requirements................................................................................................................................ 10 6.3 Physical Checks ............................................................................................................................ 11

7. Test Procedure ...................................................................................................................................... 11

7.1 Hydrostatic Test ............................................................................................................................ 11 7.2 Test Criteria .................................................................................................................................. 12 7.3 Pneumatic Test ............................................................................................................................. 12

8. Completion of Test ................................................................................................................................ 14

9. Flushing of Pipework and Equipment .................................................................................................... 15

9.1 Water Flushing ............................................................................................................................. 15 9.1.1 Arrangement ..................................................................................................................... 15 9.1.2 Velocities .......................................................................................................................... 16 9.1.3 Duration ........................................................................................................................... 16

9.2 Drying and Blowing ...................................................................................................................... 17 9.2.1 Blow Out .......................................................................................................................... 17

9.3 Performance Requirements ........................................................................................................... 17 9.3.1 Water Flushing .................................................................................................................. 17 9.3.2 Drying ............................................................................................................................. 18




9.3.3 Blow Out .......................................................................................................................... 18 9.4 Instrumentation ............................................................................................................................. 18 9.5 Vessels, Rotating Equipment, Heat Exchangers.............................................................................. 18

Appendices

Appendix A Status of Instruments During Pressure Tests




1. INTRODUCTION

1.1 Scope This document specifies the minimum requirements for the methods, tasks, scope and criteria for the pressure testing of metallic and non metallic piping systems for projects undertaken by Ma’aden within the Kingdom of Saudi Arabia. This includes the strength pressure test of the pressurized sewer and tightness test of the gravity sewers.

The following items shall not be subjected to pressure testing unless specified otherwise:

• Piping systems open to the atmosphere, including overflows and vents

• Drains to atmosphere, except the sections of the system that may be isolated via valves during operation

• Any package unit previously tested for strength purposes by the manufacturer in accordance with the applicable codes, except the leak test to be undertaken upon integration of the package into the main plant to confirm the tightness of joints

• Instrument piping or tubing between the isolation valve at the process or utility line and the connected instrument

• Instrument components as listed in Appendix A of this Specification. These components shall be tested prior to arrival at site as part of instruments scope.

The Contractor shall prepare a procedure for flushing and air blowing, which shall be approved in writing by the Employer prior to commencement.

This specification is intended to be used in conjunction with the applicable documents listed herein as well as other relevant specifications and data sheets.

1.2 Purpose The purpose of this specification is to set the minimum engineering standard for testing metallic (e.g. carbon steels, stainless steels) and non-metallic (e.g. GRP, carbon steel rubber lined) piping systems.

2. KEY TERMS AND DEFINITIONS

ASME American Society of Mechanical Engineers

ASTM American Society for Testing and Materials

BPVC Boiler and Pressure Vessel Code

BS British Standards

SBC Saudi Building Code

CNAF Compressed Non Asbestos Fiber

GA General Arrangement

GRP Glass Reinforced Plastic




ITP Inspection and Test Plan

LDT Line Designation Table

LP Low Pressure

PCC Post Construction Committee

PMCS Piping Material Class Specification

Employer Saudi Arabian Mining Company (Ma’aden) and its authorized representatives and respective affiliates.

3. REFERENCED DOCUMENTS

This specification requires compliance with the provisions of the latest revision of the relevant standards or codes of the following authorities and technical organizations, as applicable, and specifications which shall be considered to form part of this specification, where applicable.

3.1 Statutory Regulations All work performed and materials furnished shall comply with the applicable statutory regulations, codes and other requirements of the Kingdom of Saudi Arabia (including but not limited to directives of the High Commission for Industrial Security, Royal Commission regulations applicable to the Site, regulations of the Presidency of Meteorology and Environment, Saudi Building Code, and other applicable codes and regulations). The Contractor shall ensure that he is fully aware and informed of all Government laws, local ordinances, regulations and all orders and decrees of bodies or tribunals having any jurisdiction or authority over the Project and/or Site, which in any way affect the conduct of the Work. The Contractor shall at all times observe and comply with all such Government and/or Ministry laws, bylaws, ordinances, codes, regulations, orders and decrees.

3.2 Industry Codes and Standards All equipment and systems shall conform to the following:

3.2.1 International Codes and Standards

ASME B31.1 Power Piping

ASME B31.3 Process Piping

ASME B31.4 Liquid Transportation Systems for Liquid Hydrocarbons and other Liquids

ASME B31.8 Gas Transmission and Distribution Piping Systems

ASME B31.11 Slurry Transportation Piping Systems

ASME BPVC Section VII Rules for Construction of Pressure Vessels

ASTM A380 Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems




BS 7159 Design and Construction of GRP Piping Systems for Individual Plants or Sites

ISO 14692-Part 4 Petroleum and Natural gas Industries, GRP Piping-Fabrication, Installation and Operation

3.2.2 Alternative Design Codes Alternative design codes, standards and specifications referred by documents that form a part of this specification may be used if approved by the Employer.

3.3 Ma’aden Standards

Ma’aden Document Number Document Title

MD-101-SMEM-EG-PI-SPC-0002 Piping Material Class Specifications

MD-101-SMEM-EG-PI-SPC-0005 Piping Installation

MD-101-SMEM-EG-PI-SPC-0006 Shop and Field Fabrication of Piping

MD-101-SMEM-EG-PI-SPC-0013 Pipe Welding

MD-101-SMPM-PM-QA-PEI-0001 Contractor Quality Requirements

4. MATERIALS

Piping Materials shall be as detailed on the isometric drawings prepared for the installation. All piping components required for the assembly of the pipework shall be defined on the Bill of Materials (BOM) listed on the isometric drawing. The Contractor shall refer any queries with respect to piping materials to the Employer.

5. EXECUTION

5.1 Quality General quality requirements are detailed in document Contractor Quality Requirements (MD-101-SMPM-PM-QA-PEI-0001).

5.2 Testing Requirements

5.2.1 General Prior to initial operation, all installed piping shall be pressure tested except where otherwise qualified in this specification.

The test shall be hydrostatic using water unless there is a possibility of damage due to freezing; or, if the operating fluid or piping material would be adversely affected by water, any other suitable liquid may be used.

The following systems may be tested pneumatically only with written approval from the Employer and strictly to the requirements of design code selected (e.g. ASME B31.1, ASME B31.3, etc):




• Gas, steam, or vapour lines, when the weight of the hydrostatic liquid would overstress supporting structures or pipe wall

• Piping with linings subject to damage by hydrostatic liquid

• The instrument air header shall be tested with dry air, noting the additional requirements for pneumatic testing as prescribed in Section 7.3.

For HDPE pipe, manufacturer’s guidelines and procedures shall be followed.

5.2.2 GRP Piping GRP piping systems shall be hydrostatically tested after installation, preferably in smaller parts that can be tested separately.

The pressure testing of GRP piping shall be in accordance with the nominated design code (e.g. BS 7149, ISO 14692 etc). Testing medium shall be water and special care shall be taken to remove air pockets from the line to prevent damage to pipe.

Testing GRP piping systems shall include all bell/spigot joints (with o-rings as well), as these systems are prone to leak if the manufacturing/installation tolerances and pipe supports are not maintained as per the design and/or the trench preparation deviates from manufacturer’s recommendations in the case of underground piping.

The test temperature of GRP piping shall be carefully chosen (together with the installation temperature) for the section of the piping under consideration as GRP has a much higher coefficient of thermal expansion and a much lower allowable expansion stresses compared to metals. Test temperature shall not be below the design minimum or above the design maximum agreed with the GRP manufacturer.

The rate of pressure increase/decrease during test shall be within the recommendations of the applicable design code. ISO 14692 Part 4 shall be used in the absence of a more prescriptive criteria.

Temperature variation of pressure test water during the test shall be kept to limits agreed with the GRP manufacturer. The test duration and acceptance criteria is dependent on the GRP material (e.g. epoxy or phenolic material etc), joint construction and hygro-thermal properties of laminates, hence shall be closely liaised with the GRP manufacturer.

5.2.3 Rubber Lined Piping Lined Carbon Steel piping components and systems shall generally be tested as required by the design code, e.g. ASME B31.3, Chapter VII for Non-Metallic Piping and Piping Lined with Non-Metals, along with the generic requirements of this Specification.

A testing procedure shall be prepared by the Contractor for review and approval by the Employer before work may commence. This procedure shall incorporate any requirements or guidelines provided by sub contractor fabricators.

5.2.4 Gravity Sewer Gravity sewers shall be tested in accordance with SBC 701 Clause 1.12.6, with the exception that the test duration shall be one hour.




This consists of plugging the end of the building sewer at the point of connection with the public sewer, filling the building sewer with water, testing with not less than a 3 m head of water and maintaining such pressure for one hour.

5.2.5 Vessels and Equipment Vessels and equipment should in general be designed to withstand the hydro test conditions. Vessels or equipment not capable of sustaining the pressure test load and those with internals or linings that would be damaged by the test fluid may be excluded from piping system hydrostatic tests. Pneumatic testing with a suitable medium shall be agreed with the Employer.

The following equipment may be excluded from all pressure testing with the Employer’s written approval:

• Pumps, compressors, turbines and vessels if hydrostatic tests were completed by the original equipment supplier

• Equipment and piping provided by others, and specifically recommended by the supplier not to be tested provided it complies with the design code.

The pressure on any point in vessels or equipment included in the pressure test shall not be greater than the shop test pressure for that equipment as stated on the vessel drawing, supplier's equipment drawing, or data sheets. In the event the piping test pressure is greater than the vessel or equipment test pressure, the piping shall be disconnected, blinded, and tested separately. If the piping cannot be disconnected (welded connection), the system stated design pressure has to be evaluated and downgraded if necessary.

Certain types of heat exchangers are specifically designed for a low allowable differential pressure between shell side and tube side, as stated on the supplier drawings, and data sheets. These should be checked; and, if necessary, test both shell side and tube side simultaneously at a pressure differential not exceeding the specified allowable pressure.

5.2.6 Instrumentation Appendix A outlines the recommended status of instruments during testing to ensure protection.

5.2.7 Testing Methods and Pressure Testing methods for all lines shall be as specified in the Line Designation Table (sometimes called the Piping Line List).

All lines shall be tested to the pressure specified in the Line Designation Table.

5.2.8 Isolation of Instruments During Pressure Test Requirements for isolation or removal of instruments and other inline items during pressure test are as per Appendix A.




5.3 Testing Medium

5.3.1 Water Water used for hydrostatic testing of piping shall be fresh, clean and free from suspended solids and other foreign matter. It shall be with a pH value between 6 and 7 at ambient temperature. Contractor shall provide water analysis that is accepted by the Employer prior to any testing. The use of sea water is prohibited.

Potable water systems shall be tested with potable quality water.

Water used for hydrostatic testing of stainless steel piping, vessels, and equipment including those with stainless steel claddings, linings, or internals and components shall conform to the requirements listed below:

• The maximum chloride content shall be not greater than 30 ppm

• Piping, vessels, and equipment must be drained thoroughly after testing.

5.3.2 Other Mediums Acceptable other mediums for pressure testing shall be, clean, oil free air or nitrogen. Air from oil lubricated compressors shall not be used.

Air shall not be used as the testing medium unless the system can be verified to have hydrocarbon concentrations that would not lead to an explosive mixture.

If the pneumatic test requirement is maintaining the inside of piping dry (e.g. piping connected to a moisture sensitive reactor) then gas used for testing shall be dry (dew point – 40°C or lower).

If maintaining the inside of piping dry is not a requirement, then the dryness of testing air (dew point) may be matched with the dew point of the design service fluid.

Pneumatic testing temperatures shall not exceed 50°C.

6. PREPARATION FOR TEST

6.1 Planning Piping shall be divided into testing systems to enable testing of multiple pipes under one hydrostatic test. These testing systems shall include one or more lines and, if possible, connected vessels and equipment which shall be subject to written approval from the Employer. Contractors shall provide detailed procedures for pressure testing, flushing and blowing as required for the project for the approval of the Employer before commencing any activity.

The Contractor shall prepare a “Test Pack” for each section containing the following, (where applicable):

• Isometrics

• Limit of the test shown on the appropriate system data (P&ID mark-ups, location plans, etc)

• Material certificates




• Location and thickness of test spades, and calculations as necessary, to confirm thickness

• Gasket size, type and thickness at test spades/blinds. Consideration shall be given to the difference in gasket thickness (spiral wound versus CNAF) and the stresses that could be caused in piping due to the difference due to bolt up loads.

• Testing medium including chemical analyses and certificates

• Test pressure

• Location of vents and drains

• Requirements for isolation or removal of instruments and other inline items (refer Appendix A)

• Location of temporary hydrostatic test supports and details.

The test pack shall also make provision for the following information to be added following the hydrostatic test:

• Witness requirements as per the ITP

• Pressure test charts

• Test equipment calibration certificates

• Record of weld repairs and procedures, and welders employed

• Any corrective actions

• Test record/s for sign off and acceptance by the Employer.

6.2 Requirements All joints, including welds, shall be left untrimmed, unpainted, uninsulated and exposed for examination during the test.

Piping designed for vapor or gas shall be provided with additional temporary supports, if necessary, to support the weight of the test liquid.

Strainers shall be removed for flushing, and replaced with temporary spools as required for hydrostatic testing.

Contractor shall verify that any required heat treatment has been performed prior to pressure testing.

Stops on spring and constant hangers and supports shall not be removed prior to testing.

Short pieces of piping which must be removed to permit installation of blinds or blanks shall be tested separately.

Temporary pipe supports shall be used to support pipe section, where required. These temporary supports shall be inspected and accepted by the Employer prior to testing.

Lines containing check valves shall have the source of pressure located in the piping upstream of the check valve so that the pressure is applied under the seat. If this is not possible, remove or jack-up the check valve flapper.




Under no circumstances shall closed valves be used to isolate a line or any equipment for the purposes of system pressure testing. In a system all valves shall be in the open position and to isolate the system, spades or blinds shall be used downstream of any valves.

Rotating equipment shall not be included in a hydrostatic test. Equipment shall not be included in a hydrostatic test where the pressure exceeds the equipment’s design pressure. Equipment which is not subject to pressure test shall be either disconnected from the piping or blocked off during the test. Cases where equipment testing is included with the piping systems shall be subject to written approval by the Employer.

In cases where a piping system being tested extends beyond the battery limit without flanges, it shall be tested to the first block valve or set of flanges outside the battery limit, provided the outside battery limit piping is confirmed to have the same design and test pressure.

Pressure test blinds with gaskets, per the relevant piping class specification, shall be used for blanking flat face and raised face type flanges. In cases where the piping class specification requires spiral wound gaskets to be used, compressed non-asbestos fiber gaskets may be substituted at test locations for the test. Where permanent operational blinds are installed, the Contractor may elect to use these for field pressure testing.

6.3 Physical Checks Piping systems shall have been completely checked (“Punch Listed”) and released for testing.

All lines shall be checked to ensure that the entire system can be completely drained after testing.

Vents or other high point connections shall be opened to eliminate air from lines which are to receive a hydrostatic test.

All air shall be removed from the piping system by venting before hydrostatic test pressure is applied.

All elements as listed in Appendix A shall be removed.

All equipment not to be pressurized shall be isolated.

7. TEST PROCEDURE

7.1 Hydrostatic Test The normal location for the pressure test gauge shall be at grade near the pressure test pump. Readings may be made at higher points providing static head differential between grade and the point of measurement is subtracted from the specified pressure.

All pressure test records shall be made using a chart recorder unless otherwise accepted.

All pressure gauges and chart recorders used for testing shall have a valid calibration certificate issued by an internationally recognized third party testing organization. Pressure gauges are to have been recently calibrated prior to the pressure test.

The gauge shall be graduated as follows:

• For test pressures ≤ 3.5 MPa(g); to approximately twice the test pressure




• For test pressures > 3.5 MPa(g); to approximately 1.5 times the test pressure but not less than 7.0 MPa(g).

Means shall be provided to demonstrate that the test pressure is actually applied to the piping being tested, e.g. by the use of a bleeder valve.

During testing, care shall be exercised not to exceed test pressure specified on the Line Designation Table. This shall be achieved by installation of a relief valve at the pressure source and the set pressure of the relief valve shall be the test pressure plus the lower of 200 kPa or 5% of the test pressure.

The test pressure shall be maintained for a sufficient time (see Section 7.2) to inspect for any seeping, weeping or pinhole type leaks and be recorded on a pressure recorder. Any leaks shall be repaired and the lines retested.

Test and vent holes in reinforcing pads shall be open during testing, and shall be left open for operation. The hole is to be filled with stiff grease after the hydrostatic.

The Contractor shall ensure all anchors and guides are installed per the design prior to pressure test.

Flexible joints shall be tested with the piping in order to check restraining devices.

If a pressure test is to be maintained for a period of time and the test liquid in the system is subject to thermal expansion, precautions (such as surveillance by a suitably qualified person) shall be taken to avoid excessive pressure.

Sealing materials shall not be used to correct leaks at joints. Valve glands shall not be tightened to the extent that the valve cannot be operated, if necessary, valves shall be repacked.

The Contractor shall be responsible for the safe venting of piping, vessels and equipment when filling, testing and draining.

7.2 Test Criteria All welds and flanged joints shall be inspected and found free of leaks.

Any drop in pressure during the test period shall be investigated and the cause rectified. (Allowance shall be made for any effect of temperature change). The test shall be repeated after the cause of the pressure drop has been rectified.

The test pressure shall be maintained for the duration specified in the test pack after the test pressure has stabilized, and the test pump disconnected.

7.3 Pneumatic Test All items in Sections 5.3.2 and 7.1 are also applicable for pneumatic tests.

Where pneumatic testing is proposed, the Contractor shall first obtain the written permission of the Employer and observe all safety precautions and all requirements of the applicable design code (e.g. ASME B31.3).




The maximum calculated stored energy of any piping system being tested should not exceed 271 MJ as per ASME PCC-2, Article 5.1. A Risk Assessment shall be completed where stored energy exceeds 13 MJ.

All lines identified for pneumatic testing in the Line Designation Table (sometimes known as Piping Line List) shall be tested to the pressure specified therein.

Pneumatic tests shall not be performed in the rain, or whilst the piping is wet. Tests shall preferably be carried out during daylight hours.

The test pressure shall not be applied until the piping system and the pressurizing medium are at about the same temperature.

A relief valve shall be installed at the pressure source and shall be set at the test pressure plus the lesser of 70 kPa or 7% of the test pressure.

A limited access area and pressure control point shall be established. Signs which read “Pneumatic Test in Progress – Access by Permission Only” shall be posted around the perimeter of the limited access area. Only testing personnel involved in the particular operation being performed may be within the limited access area, e.g. during system pressurizing, testing personnel who will be examining the system shall be outside the limited access area.

One person shall be at the pressure control point monitoring the gauge whenever the system is pressurized.

The air shall be introduced into the piping system gradually until the pressure is the lesser of one-half of the test pressure or 170 kPa(g). At this point the pressure shall be maintained for a minimum of 10 minutes followed by a preliminary check.

Leak detection fluid shall be applied (using a chemists wash bottle or other suitable means) to all joints and connections suspected to be leaking. Ordinary household soaps or detergents are not permitted. If tightening is required to stop leaks, isolate the immediate work area from persons not necessary for the tightening operation. Personnel shall remain clear of the gasket plane projection.

The pressure shall be gradually increased in steps of one-tenths (1/10ths) of the test pressure

until the test pressure is attained. During this pressurizing stage, check seals, seats and gasketed joints for leakage after a specific pressure has been established for 10 minutes, as required.

When the test pressure has been attained, it shall be held for a minimum of one hour.

Perform a visual inspection of all joints and connections at the test pressure using leak detection fluid.

Any bubbles observed as a result of seepage shall be considered sufficient reason for non-acceptance of the system being tested. The system shall be retested following repair work.




8. COMPLETION OF TEST

A pressure test shall be considered complete when the following are finalized and accepted:

• All defective welds, defective materials, flange leaks, valve gland leaks or other such defects have been corrected and, where required, retested

• All documentation and “test pack” information shall be completed. The test pack (Section 6.1) at this stage shall also include pressure test charts, a record of all repair welding operations including record of all welding procedures used and welders employed and all other corrective operations.

After completion of the pressure test and flushing, all temporary blanks and blinds shall be removed (and noted as such on the test pack register), all operating blinds returned to proper position and all lines completely drained and the correct line class gaskets and bolting installed. Valves, orifice plates, expansion joints and short pieces of piping which have been removed shall be reinstalled with correct line class gaskets and bolting. Lines being drained after testing shall have all vents open. Lines downstream of a check valve shall be inspected to ensure complete drainage. Piping and equipment shall be completely dried. (Refer to Section 9.)

Air vents on pressure equipment shall be set in the open position prior to draining. Care shall be exercised in controlling the rate of drainage from vessels with respect to the inflow of air through the vent to ensure that the vessel is not subjected to vacuum. After vessels have been completely drained, vents, cyclones, and other internal closures that were opened before testing shall be closed.

After lines have been drained, temporary piping supports shall be removed. Spring hangers provided with stops to carry the test load shall have these stops removed after the test is complete and prior to putting the line in to operation. Lines shall be closed to prevent entry of foreign materials.

The following operations shall also be carried out:

• Instruments which were removed or blocked out for test shall be reinstalled and actuators placed in the normal operating position

• Check valves that were jacked open or the internals were removed for pressure testing shall be returned to their proper operating position

• Instruments and process lead lines that were subjected to the hydrostatic pressure test shall be blown out with dry air or nitrogen

• Vent and drain connections that were added solely for pressure testing shall be closed and seal welded as required. Drains shall have either the valve closed and plugged or, if the valve is removed, the connection plugged and seal welded as required. Insulation shall be completed after visual inspection of seal welded vents and drains.

• Strainer screens shall be removed, cleaned, and reinstalled.

Completed systems shall be flushed in accordance with Section 9.




9. FLUSHING OF PIPEWORK AND EQUIPMENT

9.1 Water Flushing In general, the initial flushing shall be carried out with fresh water prior to and/ or subsequent to pressure testing, as agreed with the Employer.

Potable water systems shall be flushed with potable quality water.

Carbon steels shall be flushed with suitable quality water with a pH of between 6 and 8.

Stainless and alloy steel lines shall be flushed with suitable quality water with a pH between 6 and 7, chloride ion content in water shall not exceed 30 ppm. The use of demineralized water should be considered.

Any piping material that can be affected by fresh or demineralized water flushing shall be flushed with air or nitrogen.

The procedure for flushing and operator safety shall be developed by the Contractor and submitted for Employer approval before implementation. The procedure shall include the following:

• Proposed work pack details of the system to be flushed

• Pump capacity, velocity of flushing water

• Temporary connection details to water source and effluent drainage system

• Flushing must not cause soil erosion or pollutants to be discharged into the open area

• It should be noted that risk of pitting corrosion is considerably diminished if the time between pressure testing and start-up (lay-up) is as short as possible. If the lay-up time is anticipated to be longer than one week, flushing with condensate or demineralised water is recommended. In such situations draining and/or blow drying of piping shall be carried out as required and openings shall be sealed and/or internal environment protected by suitable means e.g. nitrogen lay-up as per the project specifications and Specification Shop and Field Fabrication of Piping (MD-101-SMEM-EG-PI-SPC-0006).

9.1.1 Arrangement Any line mounted item or equipment which would be sensitive to damage during water/air/nitrogen flushing shall be removed, blocked off or isolated during flushing.

All in-line piping items and in-line instrument and control valves shall be removed, blocked or isolated during cleaning/flushing/air-blowing operations and shall be reinstalled after completion of the operations. Temporary spools (if) used to replace these items shall match the line size and rating of the line they are being installed in.

Water flushing requires that precautions be taken in regard to where the effluent is discharged. Water flushing shall not take place unless the effluent is connected to the appropriate plant drainage system as per the flushing procedure agreed with the Employer.

During flushing, particular care must be exercised to prevent over pressurizing or subjecting any vessel to vacuum conditions. All column and vessel vents shall be open during flushing.




Soft seated valves shall be removed prior to flushing, but where this is not possible the internal fittings shall be removed.

Flushing with equipment, vessels and tanks on-line (in one circuit) is permitted provided the pressure and/or weight of the flushing medium can be tolerated by the piping system, connected equipment and any internal instruments, fittings or other devices, which would be subject to damage, are removed. These details shall be specified in the flushing procedure schematic drawings included in the work pack.

Separators, heat exchangers and similar vessels can be used as paths for flushing, but upstream piping must incorporate suitable metallic, permanent or temporary strainers, if not, the lines must be flushed first with the equipment isolated.

All flushing outlets connections shall be provided with a basket for trapping debris.

Precautions shall be taken to ensure the water is safely drained away whilst flushing is being carried out. If air or steam blowing is to be carried out, the need for special precautions regarding the exhaust area and thrust on pipework must be considered and identified. Special attention is to be paid to ensure that electrical, electronic or any other equipment adjacent or below, is not deluged.

Temporary supports wherever used during pressure testing shall be retained until the completion of cleaning activities.

9.1.2 Velocities In general, the flushing medium velocity should equal the process design velocity however the following minimum flushing velocities should be achieved:

• Up to and including DN 200; three metres per second

• Greater than DN 200 up to DN 500; piping shall be flushed with the highest possible velocity which can be obtained from the available water source

• Piping larger than DN 500; piping shall be visually inspected followed by hand cleaning.

The use of high pressure jet flushing, such as rotating nozzles should be considered.

The Contractor shall be responsible for ensuring that the required water velocities for flushing of pipework are achieved. This will require the use of water storage and external pumping devices for the larger bore piping systems.

9.1.3 Duration In all cases flushing shall be continued for a minimum of 30 minutes. In an open system, flushing shall be continued until flushing water leaving the system is clear and free of all foreign debris.

In a closed system, flushing shall be continued until the circulating pump strainer is free of foreign debris and circulating water is clear. Unless specified elsewhere, Employer’s personnel shall determine when the system has reached acceptable cleanliness.




9.2 Drying and Blowing Piping and equipment shall be dried if required, e.g. piping designed for carrying 98% Sulfuric Acid shall be thoroughly flushed with clean water and then dried by air blowing to ensure that no moisture remains in the piping before commissioning the line on acid.

Contractor shall prepare and submit a procedure for drying pipes for approval by Employer. Drying of large diameter pipes DN900 and above shall be specifically addressed. Drying shall be done by air blowing.

During drying by air blowing, care should be exercised in the area where air is venting off, as debris in the system will be ejected. If the exhaust is close to and facing equipment such as motors, compressors or instruments, it is mandatory to install a temporary bend to deflect the venting air. Personnel must wear necessary protection and stay out of the way of the air stream.

When air blowing is taking place, care must be exercised to prevent recoil of piping. Where flanges are spread open, retaining bolts must be maintained in the flanges to prevent piping recoiling. Lines that are temporarily supported must be checked for adequacy of supports and if improperly supported, the excessive sag will not allow proper blowing.

Contractor shall supply all equipment and consumables required for air blowing.

Employer shall be informed before the start of any blowing activity.

Blow drying operation shall be performed by experienced and skilled personnel acquainted with the techniques utilized.

All pipework shall be free of dirt, grease and debris upon completion of flushing.

9.2.1 Blow Out Piping systems connected to equipment likely to be damaged due to the momentum of the debris should be flushed using a flushing stream with a much higher momentum than that of the design flow. For example, inlet lines connected to steam/gas turbines, axial flow compressors. This procedure is called blow out.

Blow out media may be LP steam, air or nitrogen, depending on availability.

Blow out operation shall be carried out according to approved procedures utilizing fully engineered equipment and trained staff.

A P&ID, LDT, and Layout GAs shall be prepared for the blow out operation and shall be approved by the Employer before implementation. LDT shall nominate the recommended momentum of the blow out stream.

9.3 Performance Requirements

9.3.1 Water Flushing The Employer shall be informed before the start of any flushing activity.

Flushing operations shall be performed by experienced and skilled personnel acquainted with the technique for flushing.

Flushing operations may be carried out in conjunction with hydrostatic testing of complete systems in order to minimize the number of flange connections to be opened.




In order to avoid unnecessary consumption of service gaskets, all temporary connections for flushing operations shall be installed using temporary gaskets suitable for the operating condition. All temporary gaskets shall be supplied by the Contractor.

The Contractor shall provide suitable temporary connections to flushing water source nominated by the Employer and connections to storm water drainage for the effluent water. The flush water flow shall not exceed the design capacity of the storm water drainage system and this shall be confirmed with the Employer prior to proposing the flushing procedure.

The Contractor shall provide suitable circulation and/or flushing pumps.

The Contractor shall provide suitable temporary pipe connections, hose connections, blind flanges, temporary gaskets, temporary strainers and dummy spools as required for flushing.

The Contractor shall restore all systems to their design conditions after cleaning and flushing.

9.3.2 Drying The effluent from drying shall meet the moisture content requirements at the exit points as specified in the drying procedure.

9.3.3 Blow Out The effluent from blow out shall meet the discharge requirement as specified in the blow out procedure, e.g. repeat procedure until clean polished target plates are achieved.

9.4 Instrumentation In general all instruments in the system to be flushed shall be isolated by test blinds, or removed unless otherwise permitted.

Relief valves and rupture discs shall be removed or blanked off from equipment or the piping system prior to flushing.

Orifice plates, flow nozzles or other similar restrictions shall not be installed until the system is flushed.

Flanged control valves shall be removed. Where there is no bypass, a spool piece shall be installed.

Line mounted instruments such as rotameters and positive displacement meters shall be removed and spool pieces shall be installed. Where there is a bypass, the open ends shall be flushed for a short period, and then blinded.

Locally mounted indicating pressure gauges shall be blocked off or removed and their connections plugged during flushing.

Level instrument floats, located inside vessels or float cages shall be blocked off and opened to the air.

9.5 Vessels, Rotating Equipment, Heat Exchangers Vessels shall only be flushed after the feed line has been thoroughly cleaned and specific agreement has been obtained from the Employer.

Where possible, all connecting pipes should be flushed starting at the vessel in order to avoid disassembling of flange connections. Filling of those vessels shall be done using the lowest possible point for flushing connection.




Flushing into process tanks is allowed providing the tank is thoroughly cleaned after flushing.

Pumps, compressors and other rotating equipment shall not be flushed. Flange connections to such equipment shall be disconnected prior to flushing and equipment shall be protected with blinds.

Heat exchangers may be flushed through if the feed line is thoroughly cleaned first.




Appendix A Status of Instruments During Pressure Tests




Table A-1 : Status of Instruments During Pressure Test

Instrument Block and Vent

Remove1 Blind Refer to Notes

Analyzers X

Control valves – except regulators and pressure balanced ≤ DN 150

X 2/4

Control Valves – pressure balanced ≤ DN 150 X 2/4

Flow Instrumentations – D/P Cell and Bellow Types

X

Flow Instruments – Vortex Type X

Flow Instruments – Rotameters X

Flow Meters – positive displacement type X

Flow Meters – turbine type X

Gauge Glasses X

Level Instruments – displacer type X

Level Instruments – D/P cell and bellows type X

Orifice Plates X 3

Pressure Gauges X

Pressure Instruments – all types X

Pressure Regulators X

Pressure Switches X

Temperature Gauges X 5

Temperature Transmitters X 5

Relief Valves X

Expansion Joints X

Filters X

Flanged Ball Valves X 6

Notes: 1. Remove these items during pressure test. 2. Welded-in items to be closed during test, by-pass to be opened. 3. Install after testing and line flushing. 4. If flange valves are to be removed, consider installing a spool piece across the flanges of the

valve so that the whole line can be included in the test. 5. Thermowells may be left in during testing. 6. Manual ball valves may stay in open position.