Sunday, October 3, 2010

Above Ground Piping Procedure

1. Scope
1.1 This procedure shall be applied for the pre-fabrication, installation, examination, pressure testing and cleaning of above ground piping, including OGM piping and Well Head piping for FSF projects.

2. Reference Documents
a) Contract documents
b) Design documents
c) OWNER’s specification:
1) PDOC-SP-PIP-002, Specification for Piping Design and Layout
2) PDOC-SP-PIP-003, Specification for Pressure Testing of Piping Systems
3) PDOC-SP-PIP-004, Specification for Piping fabrication
4) PDOC-SP-PIP-005, Specification for Piping Welding
5) PDOC-SP-PIP-011, Specification for Piping Material
d) ASME B31.3, Process Piping
e) ASME IX, ASME BOILER AND PRESSURE VESSEL CODE
f) ASME B31.4, Liquid Transportation Systems for Hydrocarbons
g) API 1104, Welding of Pipelines and Related Facilities
h) PFIES-5, Cleaning of Fabricated piping
i) In case where more than one code or standard apply to the same condition, the most stringent shall be followed during construction. In the event of a conflict between them, the OWNER shall be consulted and a ruling in writing shall be obtained before any work is started.

3. Pipe Pre-fabrication
3.1 General
3.1.1 The approved project specification shall be used.
3.1.2 Competent welders who have passed the examination as per approved procedures Welding Procedures (PDOC-587B-PR--006) and obtained the certificates or permits shall do piping fabrication & installation welding.
3.1.3 All materials and pipe fittings shall be handled, stored and delivered according to applied procedure.
3.1.4 Piping shall be blasted and painted/coated according to applied procedure.
3.1.5 Prefabrication shall be done according to the approved isometric drawings; the prefabrication limit shall be marked on the isometric drawings by construction technician.
3.1.6 Piping welding shall be in accordance with approved welding procedure specifications.
3.1.7 The material requisition for pipe and fittings shall be submitted three (3) days earlier by construction crew, after the material requisition verified by related technician, materials shall be delivered to the personnel who is appointed by construction crew and OWNER, and stored in good condition by classification. Before prefabrication and line up, materials and fittings shall be carefully checked in order to identify quality, thickness, type and specification.
3.1.8 Any deformed pipe fittings or damaged face of flange and valve shall be replaced and recorded; all unqualified materials shall be clearly marked to avoid being misused for next time.
3.2 Pipe cutting
3.2.1 Pipe can be cut by machine or Oxy-acetylene flame, for the carbon steel pipe smaller than 2” can be cut by machine, stainless steel pipes cannot be cut by flame welding. The stainless steel pipe which is smaller than 2” can be cut by machine, larger than 2” stainless steel pipe can be cut by machine or plasma cutting .All scales and other foreign material on the surface shall be removed after cutting, galvanized pipe shall be cut by cutting machine.
3.2.2 Considering prefabricated materials size may be reduced for cutting, welding, and grinding, pipe shall be more than 1-2mm when it is prepared to be prefabricated, pipe shall be more than 100mm for surplus at erecting fixed spots.
3.2.3 Marking shall be transferred on each section cut material and clearly marked the Heat No., Thickness, material grade, all cut material which have not been marked or identified shall not be used.
3.2.4 Pipe cut length less than 1.5 times the outside diameter shall not be used.
3.3 Beveling of the edge
3.3.1 Bevel shall be processed by machine or Oxy-acetylene flame, scales shall be removed by grinder, bevel angle shall meet welding requirement. The water, oil or other foreign materials shall be removed by wire brush or cotton waste before welding, for stainless steel material; it shall be cleaned by stainless wire brush.
3.3.2 The appearance of bevel shall be checked after beveling, and free from slag, crack or other defects. After bevel is checked, welding shall be done immediately and document shall be recorded.
3.4 Pipe fit-up
3.4.1 For pipe fit-up, the clearance and angle between bevels shall be as per specification. For pipe of the same nominal wall thickness, the maximum offset or misalignment of the abutting pipe ends shall not exceed one-sixteenth (1/16) inch. When the unequal wall thickness to be joined, the external offset shall not exceed one-eighth (1/8) inch and internal offset shall not exceed three thirty-second (3/32) inch, if these values are exceeded, the excess thickness of the heavier end shall be machined or ground back from the bevel on a one-to-four (1 to 4) taper.
3.4.2 Welding surface and geometric size shall comply with the requirement in the ASME B31.3.
3.5 Pipe welding
3.5.1 Welding shall be in accordance with the welding procedure specifications.
3.5.2 Welding consumable requisition and storage shall comply with welding material control procedure.
3.5.3 After the welds completed, the surface of welds shall be cleaned and finished to remove all slag, scale etc. welder shall mark his embossed stamp number at spot 50mm far from welding seam, stainless steel pipe shall be marked by painting, welder number shall be marked at the correspondent position on the isometric drawings and welding records shall be made at the same time.

3.5.4 When the nipples have been prefabricated, records shall be made, the temporary supports are needed during handling the prefabricated nipples to prevent damage to paint or deformation of nipples. Hand over formalities shall be arranged, registered when the nipples are transported from the mill (shop), the isometric drawing and all kind of construction records shall be provided when they are handed over. The prefabricating status and welder number shall be marked on the isometric drawing.
3.5.5 Non-destructive test shall be in accordance with OWNER’s specified codes and codes & standards.
3.6 Pipe supports prefabrication
3.6.1 The materials used for supports shall conform to the code requirement, the material’s types, specifications, processed size, and welding shall be in accordance with drawings.
3.6.2 Flame welding can not be used for making holes on the pipe supports, the support welding surfaces shall be checked to ensure there are no crack or other defects.
3.6.3 The supports shall be blast cleaned and painted the material quality and type; size shall be clearly marked and stacked in a good condition by classification.
3.7 Thread processing
3.7.1 All pipe threads shall be fabricated at shop, the selected pipe materials used for thread shall be in accordance with drawing, the threads and seal faces shall be protected in a good manner.

4. Piping Installation
4.1 Valve examination prior to valve installation
4.1.1 Should check the valve’s specification, type, and identification tag and factory qualification certificate in accordance with the engineering drawings.
4.2 Relief valve calibrating
4.2.1 Prior to installing the relief valves, if they did not have the vendor’s calibrate certificate, they shall be calibrated as per PI&D drawings.
4.3 After the following have been completed the piping can be installed.
4.3.1 All civil work related with pipe have been checked and accepted and can meet installation requirement.
4.3.2 All equipment connected with pipe have been aligned, secured and accepted.
4.3.3 All valves and fittings have been checked and accepted. Pipe prefabrication has been handed over.
4.4 No iron or steel tools can be used for knocking the stainless steel pipe.
4.5 During installation asbestos blind shall seal flanges, which are connected with vessels, equipment or pump. The fixed welding joint of pipe that is connected with the dynamic equipment shall be far from the equipment.
4.6 Valve installation
4.6.1 Valve shall be installed as per requirement in PDOC-SP-PIP-012.
4.6.2 Prior to installation, all valves shall have sufficient clearance to facilitate removal of the bonnets, plugs and internals, the type number and tag shall be verified as per drawings, installation direction shall be identified according to medium flowing direction. Flange seal face shall be checked to ensure no damage to them, the operative mechanism and driving units should be regulated as necessary, butt welding valves had better open during welding.
4.6.3 Care shall be taken to avoid damage to the instruments when installing adjustable valves.
4.7 Supports and brackets installation
4.7.1 Supports, brackets, hangers shall be secured and adjusted, guiding and sliding supports shall be evenly and securely installed.
4.7.2 When the hangers and supports are welded with piping, the welding seams shall be carefully inspected.
4.7.3 After the pipe has been installed, the location and patterns of the supports or brackets shall be checked one by one as per drawings.
4.8 The position of the pipe fittings which are removed for testing and purging and both inlet & outlet of pump or other equipment shall be mounted with temporary gaskets. Formal gaskets shall be used in other location.

5. Pressure Test
5.1 Pressure test shall be carried out according to ASME B31.3 (Process Piping) Code and OWNER specification for pressure testing of piping systems (PDOC-SP-PIP-003).
5.2 Prior to testing piping system, the following items shall be completed:
5.2.1 Construction for piping system has been completed as per drawing.
5.2.2 Non-destructive tests have been completed and accepted.
5.2.3 All buried pipe’s coordinates, elevation, grade, pipe basis and padding have been verified and accepted, all temporary reinforcement measures have been verified to ensure that they are tightly secured.
5.2.4 All QC forms and hydro test package shall be documented according to QUALITY PLAN & PROCEDURE and accepted by QC department and other related divisions.
5.2.5 Test gauges have been calibrated, the accuracy shall be no less than 1.5 grades and graduation value shall be 1.5-2.0 times of the maximum pressure, at least two gauges are needed in one system, and pressure recorder which have indicating needle for pressure testing and temperature record.
5.2.6 The location of gauge and blind board shall be marked in the test system flow diagram.
5.2.7 The test application shall be verified, approved and accepted by related department.
5.2 All the equipment, instruments and pipe fittings which are not included in the test system shall be segregated or removed before testing; the blinding location shall be clearly marked and recorded.
5.3 Check the process flow and open the relative valves before pressure-test. In case flow direction of testing medium is reversed to flow direction of retaining valve, the valve’s core that has been taken out shall be labeled, and records made, and mounted after testing and cleaning.
5.4 Testing Medium
5.4.1 The liquid piping shall be hydro-tested. The testing medium shall be water unless there is the possibility of damage due to freezing or to adverse effects of water on the piping or the process. In that case another suitable nontoxic liquid may be used. If the liquid is flammable, its flash point shall be at least 49°C (120°F), and consideration shall be given to the test environment; the gas line shall be tested use by air or according design document.
5.5 Test pressure
5.5.1 Test pressure shall be confirmed as per the Line List in design drawings.
5.5.2 When it is not specified in drawings:
Hydrostatic test pressure shall be no less than 1.5 times of design pressure, and air test pressure shall be 1.1 times of the design pressure, if the design temperature is higher than test temperature, the minimum testing pressure of the pipe shall conform to the requirement of ASME.B 31.3
5.6 Testing procedure
5.6.1 Testing water shall flow into the piping system from the lowest drain, all air in the system must be purged out from the highest vent, and one gauge must be placed at the highest position.
5.6.2 Hydrostatic test pressure shall slowly rise. After the pressure reaches the test pressure, it shall be held for one hour, check the piping thoroughly, include but no limited to the welding seam, valve, flange. The test can be accepted if there are no leaks and pressure-drops after check of all piping system. All leaks shall be repaired if they are found. Prior to repair, the pressure in the piping shall be discharged from system; repair carrying pressure is not permitted.
5.6.3 Safety measures during testing shall strictly comply with the applicable safety codes and standards.
5.6.4 Testing shall be approved by the OWNER, records shall be completed after testing, and the records will compose part of the Q.C. turnover documentation.

6. Piping Cleaning and Purging
6.1 Prior to cleaning and purging piping system, the following conditions shall be met.
6.1.1 Make up the purging and cleaning flow diagram for piping system. The purging, cleaning direction and sequence shall be clearly marked on the flow diagram.
6.1.2 Pressure test of piping system has been completed and accepted.
6.1.3 All orifices, venturi tubes, nozzles, strainers, adjustable valves, flow meter shall be removed from piping system and replaced with nipple jointing.
6.1.4 All pipes or equipment that is not included in testing system for cleaning and purging shall be segregated from system.
6.1.5 System has been temporary reinforced.
6.2 The purging by water shall be done continuously, the discharge pipe shall be near the ditch or drains well, If design has not related stipulations, cleaning result can be accepted at the condition that the water quality at both the inlet and outlet of piping are the same.
6.3 When instrument air or industry air is used for air drying. If there is no water, rust, dust or any other foreign material from outlet drying shall be considered as accepted.
6.4 The OWNER representative and operations personnel at their option shall be present during drying, and cleaning of pipes. The records of cleaning and purging shall be made after purging.

7. Restoration of Piping System
7.1 After piping system has been accepted, system shall be restored immediately. All orifices, venturi tubes, nozzles, strainers adjustable valves, flow meters and retaining valves which have been removed from system for testing and purging shall be installed as per drawing. All blind boards shall be removed and all temporary gaskets shall be replaced with formal gaskets.
7.2 Pipes that are connected with dynamic equipment shall be realigned without extra load.
7.3 All temporary supports that are installed during testing shall be removed. All hangers and other brackets shall be examined and adjusted as per drawing.

8. Construction Quality Records and Inspection Reports
8.1 Construction quality records shall be made synchronously with construction and shall reflect the progression of, these records shall be managed by an appointed Q.C. clerk and audited by QC engineers and technicians.
8.2 Inspection reports shall be documented (filled out) by QC engineer to reflect the real examination contents and quality status, and approved by OWNER’s representative.
8.3 Construction quality records for blasting and painting shall be recorded accordingly as per blasting and painting procedure and insulation procedure. (Refer to PDOC-587B-PR-MEC-001 and PDOC-587-PR-MEC-002)

9. Revision Note
9.1 This procedure shall be revised if it is found to be inadequate for the purposed work upon completion of engineering/ now construction practice/ new site information or as requested by OWNER.

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