| Purpose | 2 | |
| Scope | 2 | |
| Related Documents | 2 | |
| Materials | 3 | |
| Equipment | 3 | |
| Foundations | 3 | |
| Lines, Grades, and Measurements | 3 | |
| Pipe Installation – General | 3 | |
| Excavation and Backfill | 3 | |
| Hydrant Installation | 4 | |
| Installation of Ductile Iron Piping | 4 | |
| Qualifications Required for Welding Procedures, Welders, and Welding Operators for Carbon Steel, Alloy, and Stainless Steel | 5 | |
| Weld Joint Preparation | 5 | |
| Welding Procedure | 5 | |
| Qualifications Required for Brazing Procedures, Braziers, and Brazing Operations | 5 | |
| Silver Brazing | 5 | |
| Threaded Joints and Thread Sealant | 6 | |
| Coating Underground Steel Pipe and Copper Tubing | 6 | |
| Cleaning | 6 | |
| Piping Tolerances | 6 | |
| Inspection | 6 | |
| Testing | 6 | |
| Disinfection of Potable Water System | 7 | |
| Miscellaneous | 8 | |
| Patching, Replacement, and Modification of Existing Work | 8 | |
| Prefabrication of Pipe | 8 | |
| Corrosion Control Features | 8 | |
| Highway and Railroad Crossings | 9 | |
| Holiday Spark Testing – Underground Piping | 11 | |
| Casing Details – Crossing Under Railway or Roadway | 12 | |
| Casing Size and Wall Thickness | 12 | |
| Miscellaneous Materials | 13 |
1. PURPOSE
1.1 This specification defines for the contractor the requirements for fabricating and installing metallic underground pressurized process and firewater piping.
1.2 Refer to 4API-670222 for fabrication requirements of nonmetallic piping systems.
2. SCOPE
2.1 This specification applies to all metallic pressurized underground process, potable, and firewater piping systems within the designated battery limits of a facility.
2.2 This specification must be used in conjunction with the following specification:
4WCE-670200, Fabrication and Erection of Process Piping
2.3 The scope of work required by the contractor includes (but is not limited to) fabricating, cleaning, testing, as well as providing and installing all pipe, pipe fittings, coatings, valves, gaskets, bolts and nuts, welding rod, and valve packing as required for the complete installation of pressurized underground piping systems. Fabrication and inspection of all piping shall be according to ASME B31.3, except as modified herein.
3. RELATED DOCUMENTS
3.1 Air Products Engineering Documents
4ACS-640101 Reinforcing Steel
4ACS-640102 Concrete Work
4API-CAPU007 Piping Class Specification APU007 for Underground Potable and Cooling Water Service
4API-CAPU010 Piping Class Specification APU010 Factory Mutual Rated for Underground Firewater Service
4API-57990 Firewater Protection and Underground Utility Equipment
4API-670222 Nonmetallic Pressurized Underground Process, Potable, Utility, and Firewater Piping
4APL-20001 Pipelines, External Coatings for Underground Service
4WCE-670200 Fabrication and Erection of Process Piping
4WEQ-6804 Painting and Corrosion Protection of New Construction for Design Temperature to 649°C (1200°F)
4WPI-EW44001 Pressure Testing of Process Piping and Equipment
670.840 Pipelines, Cathodic Protection Systems
670.850 Pipelines, Test Stations – Cathodic Protection
Form 7935 Holiday Spark Testing – Underground Piping
QC-200A Pressure Test Procedure (Form)
QC-200B Pressure Test Flowsheet Procedure (Form)
326263A Standard Underground Piping Details
3.2 The American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code
B31.3 Process Piping
3.3 American Water Works Association (AWWA)
C651 Disinfecting Water Mains
3.4 National Fire Protection Association (NFPA)
24 Installation of Private Fire Service Mains and Their Appurtenances
3.5 All codes, standards, and specifications shall be the latest edition in force at the time the contract is awarded.
4. MATERIALS
4.1 All material, when specified herein or on the contract drawings, shall be of first-class quality, free from defects and imperfections, of recent manufacture, unused, of the classification and grade specified and shall be according to these specifications and Air Products engineering standards.
4.2 Refer to 4API-57990 and Appendix A for acceptable miscellaneous material and equipment descriptions.
5. EQUIPMENT
5.1 Refer to Standard Underground Piping Details, 326263A, for installation requirements for the following equipment:
| Valves | Hydrant Monitors |
| Valves for Deck Pipes | Tools |
| Valve Boxes and Wrenches | Hose |
| Service Boxes and Key Stops | Hose Reels |
| Hydrants | Hose Reel Nozzles |
| Monitor Nozzles | Hose Reel Covers |
6. FOUNDATIONS
6.1 Foundations, as shown on the contract drawings, shall be constructed according to engineering specifications 4ACS-640101 and 4ACS-640102.
7. LINES, GRADES, AND MEASUREMENTS
7.1 The contractor shall lay out the work and establish elevations and grades according to the contract drawings. The contractor shall verify all dimensions by actual measurement at the site and shall refer any differences between the information on the drawings and existing conditions to the Air Products field representative for resolution.
8. PIPE INSTALLATION – GENERAL
8.1 See 4WCE-670200.
9. EXCAVATION AND BACKFILL
9.1 Due regard for safety shall be constantly observed during excavating activities and work permits issued according to safety and plant facility procedures. The contractor shall excavate whatever substance is encountered for all piping, manholes, pits, foundations, and other underground work. Trenches shall be of sufficient width for installation and inspection of pipe. The bottom of the trench shall be trimmed so that the lower portion of pipe is continuously supported on undisturbed soil until the slope of pipe is uniform between established elevations.
9.2 If rock or shale is encountered, a sand cushion shall be provided to continuously support the pipe. The thickness of the sand cushion shall be as shown below unless superseded by the contract drawing.
| Pipe Size Nominal | Sand Thickness |
| < 150 mm (6 in) | 75 mm (3 in) |
| 200 mm (8 in) to 500 mm (20 in) | 100 mm (4 in) |
| > 500 mm (20 in) | See Contract Drawing |
9.3 The depth of the piping for the various underground lines shall not be less than that shown on the contract drawings.
9.4 After the pipe sections have been pressure tested, holiday spark tested according to paragraph 18.2, inspected and approved by the Air Products field representative, the excavation shall be cleaned of trash and debris. Rocks and stones shall not be dumped directly on the pipe when backfilling. The backfilling material shall consist of the excavated material or borrow of sand or material specified on the contract drawings. Backfill shall be placed in layers not to exceed 225 mm (9 in) thickness and properly moistened to approximate optimum soil compaction. Each layer shall be compacted by hand or machine tampers, or by other suitable means, to a density that will prevent excessive shrinkage or settlement. The backfill shall be brought to a suitable elevation above grade to provide for anticipated settlement or shrinkage. Excess excavated material shall be disposed of on the site as directed.
9.5 The backfill shall be placed around manholes, pits, and other work. This shall be clean subsoil material placed in 225 mm (9 in) layers. Each layer shall be thoroughly compacted.
9.6 Cinders shall not be used for backfill.
10. HYDRANT INSTALLATION
10.1 Hydrants shall be installed according to the details of 326263A.
11. INSTALLATION OF DUCTILE IRON PIPING
11.1 Push-on, mechanical joint pipe restraints shall be used according to paragraphs 11.8 through 11.12.
11.2 The contractor shall thoroughly clean the inside of all pipe before laying the pipe in the trench, and open ends shall be plugged when work is stopped to prevent stones or dirt from entering. If minor changes in grade or direction of pipe are necessary, the pipe may be shifted in the joint. With bell and spigot joints, the limiting factors are:
11.2.1 Joint opening shall not exceed 19 mm (0.75 inches).
11.2.2 Caulking space at the face of the bell shall not be less than 6 mm (0.25 inches) in width. Fittings shall be used for making offsets and sharp bends. Reducers shall be used for changing pipe sizes.
11.3 Pipe push-on joints shall be assembled according to the recommendations and directions of the supplier, using materials and tools specified to make a pressure-tight joint. The supplier shall be as specified in 4API-CAPU007 and 4API-CAPU010.
11.4 Mechanical joint pipes and fittings shall be joined together by centrally locating the spigot in the bell and positioning the rubber gasket seals. Before positioning the rubber gasket seals, the surfaces with which it comes in contact shall be brushed thoroughly with a wire brush and soapy water.
11.5 When tightening the gland bolts, it is essential that the gland be brought up toward the pipe flange evenly, maintaining the same distance between the gland and the face of the flange at all points.
11.6 The normal range of bolt torques to be applied to standard cast iron bolts in a joint are:
| Bolt Size mm Inches | Range of Torque
(Foot-Pounds) |
|
| 16 5/8 | 40 to 60 | |
| 19 3/4 | 60 to 90 | |
| 25 1 | 70 to 100 | |
| 32 1 1/4 | 90 to 120 |
11.7 The above torque loads shall be applied with torque measuring or indicating wrenches.
11.8 For push-on pipe all hydrants, tees, plugs, and bends shall be anchored to resist the thrust due to a water pressure of 13 bar g (200 psig) by means of bolted rods, tie rods and pipe clamps, concrete thrust blocks, or a combination of rods and thrust blocks according to NFPA 24, Section 8-6, FM 3-10, or as shown on the contract drawings.
11.9 The mechanical joint pipe shall be restrained by a ductile iron retainer gland instead of tie rods or thrust blocks. Joint deflection shall be limited to 3° when this gland is used.
11.10 Cor-ten steel “Super Star” Figure No. SST 7 tie bolts in conjunction with Cor-ten steel rods, washers and nuts, as well as Tie anchor III are also acceptable restraints. These tie bolts are manufactured by Star National Products, 1323 Holley Avenue, Columbus, OH 43216.
11.11 MEGALUG joint restraints are also acceptable restraints. MEGALUGS are manufactured by EBAA IRON, P.O. Box 857, Eastland, TX 76448.
11.12 The contractor shall apply a thorough coating of “Sovapon-Mastic Black” on all rods, clamps, and exposed metal to protect against corrosion.
12. QUALIFICATIONS REQUIRED FOR WELDING PROCEDURES, WELDERS, AND WELDING OPERATORS FOR CARBON STEEL, ALLOY, AND STAINLESS STEEL
12.1 See 4WCE-670200.
13. WELD JOINT PREPARATION
13.1 See 4WCE-670200.
14. WELDING PROCEDURE
14.1 See 4WCE-670200.
15. QUALIFICATIONS REQUIRED FOR BRAZING PROCEDURES, BRAZIERS, AND BRAZING OPERATIONS
15.1 See 4WCE-670200.
16. SILVER BRAZING
16.1 See 4WCE-670200.
17. THREADED JOINTS AND THREAD SEALANT
17.1 See 4WCE-670200.
18. COATING UNDERGROUND STEEL PIPE AND COPPER TUBING
18.1 Unless otherwise specified on the contract drawings, underground pipe and tube shall be protected by one of the coatings listed in Section 4, External Coatings, of specification 4APL-20001, Pipelines, External Coatings for Underground Service.
18.2 Coated pipe shall be handled carefully to prevent damage to the coating. Small imperfections caused by improper application of the coating or improper handling of the coated pipe might seriously affect its protection value. After installation, all coatings shall be spark tested to detect holidays or defects. All defects detected in this test shall be repaired to provide continuity in the coating and then retested. Holiday tests shall be witnessed and approved by the Air Products representative or designee. Holiday testing shall be performed according to Section 7, Holiday Testing, of specification 4APL-20001, External Coating for Underground Service.
18.2.1 The contractor shall be responsible for completion and verification of Form 7935, which will be provided to the contractor by the Air Products field representative. After testing and repairing, this document shall be signed by both parties and shall be retained in their files.
19. CLEANING
19.1 See 4WCE-670200.
20. PIPING TOLERANCES
20.1 See 4WCE-670200.
21. INSPECTION
21.1 See 4WCE-670200.
22. TESTING
22.1 Testing shall be as directed by the Air Products field representative, according to 4WPI-EW44001.
22.2 Tests are to be conducted for tightness of lines and joints, valve bonnets, valve packing, and other fittings. Refer to 4WPI-EW44001 and QC200B for testing media and test pressures.
22.3 All tests shall be performed in the presence of and to the satisfaction of the Air Products field representative. The contractor shall notify the Air Products field representative 24 hours in advance of any test performance.
22.4 Due regard for safety shall be constantly observed.
22.5 Testing Ductile Iron Systems
22.5.1 Before obtaining final approval of the fire protection system by the local and/or state inspector, the contractor shall provide a written statement, countersigned by the Air Products field representative, to the effect that the work has been completed according to the approved specifications and plans. Tests shall be made before the joints are covered so that any leaks may be readily detected.
22.5.2 All underground pipelines in this system shall be tested at a pressure of 13 bar g (200 psig) for a period of not less than two hours (or for the length of time specified by the local authority), or at a pressure which exceeds by 3 bar g (50 psig) the prevailing maximum static pressures above 10 bar g (150 psig).
22.5.3 All tests shall be made in the presence of the local and/or state inspector and the Air Products field representative.
22.5.4 Leak Test: A suitable means shall be provided by the contractor for determining the quantity of water lost by leakage during the hydrostatic test. At the specified test pressure, leakage shall not exceed the following:
22.5.4.1 The amount of leakage at the joints shall not exceed two quarts per hour per 100 joints, irrespective of pipe diameter. The leakage shall be distributed over all the joints. If such leakage occurs at a few joints, the installations shall be considered unsatisfactory and the necessary repairs made.
22.5.4.2 During the measured leak test and after all the air has been expelled from the system, the test pressure shall be maintained by use of a hand pump arranged to replace losses with measured amounts of water from a calibrated tank. Before conducting the leak test, every hydrant shall be opened, flushed, and closed to produce water hammer simulating actual fire fighting conditions.
22.5.5 After the system has been completed and before it is permanently filled with water, the contractor shall thoroughly flush out the system through the hydrants. Water velocities of 1.5 to 2 m/sec (5 to 6 ft/sec) must be maintained to move the larger obstructing materials from the underground piping. To obtain these velocities, the following flows shall be established:
DN150 (NPS 6) Pipe – 31.5 liters/sec (500 gpm)
DN200 (NPS 8) Pipe – 63 liters/sec (1000 gpm)
22.5.6 The contractor shall be responsible for completion and verification of Form QC-200A, Pressure Test Procedure (found in specification 4WPI-EW44001) after testing and repairing of all piping and/or vessels, as required. This form will be provided by the Air Products field representative. After the completion of all tests, it shall be signed by both parties and retained in their respective files.
23. DISINFECTION OF POTABLE WATER SYSTEM
23.1 Potable water systems shall be disinfected before use. The system shall be disinfected as required by state and local regulations using AWWA C651 as a guide.
23.2 The pipe system shall be flushed with clean, potable water until dirty water does not appear at the points of outlet.
23.3 Following the first flushing, a treatment with chlorine is recommended.
23.4 Following the treatment, the system shall be flushed with clean, potable water until chlorine does not remain in the water coming from the system, or until the chlorine residual is no greater than the local water source.
23.5 The procedure shall be repeated until a bacteriological examination according to AWWA C651, Section 7 shows that contamination does not exist in the system.
23.6 Documentation indicating that a bacteriological examination has shown the system to be properly disinfected shall be given to the Air Products representative. The documentation shall include the bacterial test results certifying the water sampled from the new pipe to be free of coliform bacteria contamination, and to be equal or better than the bacteriologic water quality in the distribution system feeding the new pipe.
24. MISCELLANEOUS
24.1 See 4WCE-670200.
25. PATCHING, REPLACEMENT, AND MODIFICATION OF EXISTING WORK
25.1 See 4WCE-670200.
26. PREFABRICATION OF PIPE
26.1 See 4WCE-670200.
27. CORROSION CONTROL FEATURES
27.1 Cathodic Protection Test Stations
27.1.1 Test stations to permit making corrosion surveys and cathodic protection system performance tests shall be installed along the pipeline at the locations shown on the construction drawings. Details of construction and material requirements of these test stations are shown in 670.840 and 670.850. It is imperative the proper color code and terminal connection for the test leads be followed to prevent confusion in the interpretation of test data taken after pipeline construction is complete.
27.1.2 Test stations shall be marked and identified by the actual pipeline station number of the white test lead. Also, the distance from the test station to the centerline of the pipe shall be marked on the test station cover (inside) with a felt tip marker, weld marking paint, or equal.
27.1.3 Test leads and bond wires shall be connected to the pipeline by a thermite welding cartridge suitable for use on high stress pipe. Figure 12 of 670.850 shows how this shall be done. Test leads shall not be attached at locations of known major stresses, such as bends or welds.
27.1.4 All test leads shall be attached to the pipeline before pressure test.
27.1.5 The contractor shall exercise extreme caution during the backfill operation to prevent damage to the test station wiring and shall retest for wire continuity immediately after backfilling. Pipe to casing resistance shall be 0.5 ohms minimum. Wire continuity shall be 0.0 ohms. All broken leads shall be repaired.
27.1.6 The construction drawings will specify if the test stations are to be post (P) or vent (V) mounted or be a ground box (GB).
27.2 Test Stations
27.2.1 When more than one Air Products pipeline is installed in a trench, all of the lines shall be electrically bonded together with appropriate test leads as described in the contract documents.
27.2.2 Details of construction of the bond stations are shown in 670.850.
27.2.3 The location of all bond stations are shown on the construction drawings.
27.3 Insulated Joints
27.3.1 Insulated joints shall be installed at the locations identified in the above ground construction drawings.
27.4 Information from Contractor
27.4.1 All written reports and logs shall be typed and shall be signed by the operator, the pipeline contractor, and the Air Products representative. The following information is required: Electrical isolation report (paragraph 28.3.8). Copies of the above reports shall be submitted to the Air Products representative.
28. HIGHWAY AND RAILROAD CROSSINGS
28.1 Casings
28.1.1 Casings, where specified on contract drawings, shall be provided to the size and wall thickness as specified in Figure 1.
28.1.2 Casings need not have a special protective coating unless specified in the project scope. Mill lacquer is acceptable when no protective coating has been specified.
28.1.3 Mill reject pipe is acceptable unless new and/or coated pipe is specified in the project scope.
28.1.4 The minimum number of pipeline casing insulators required shall be calculated by the following equation and rounded off to the next higher number:
N = + 3
Where: N = Number of casing insulators
L = Length of casing pipe (feet)
The insulators shall be installed according to Figure 1.
28.2 Highway and Railroad Crossings
28.2.1 The pipeline construction at all highways, railroads, and principal access road crossings (including all details incidental to the installation of such crossings) shall be according to such specifications as may be required by the authority having jurisdiction and such specifications herein as may be applicable.
28.2.2 All city, county, state, or railroad (AREA) regulations relative to the maintenance of traffic, placing of danger signals, flares, and barricades shall be followed. All costs of compliance shall be borne by the contractor.
28.2.3 All crossings of roads having a paved surface shall be accomplished by jacking or boring unless otherwise indicated on contract drawings. Slick boring is permitted for uncased crossings.
28.2.4 Each casing shall be tested for complete electrical isolation of the metallic pipeline and casing according to paragraph 28.3.4
28.2.5 All casings shall have insulators (as required), end seals, and vent pipes as required on contract drawings with a vent cap as shown in Figure 1.
28.3 Electrical Testing
28.3.1 General
28.3.2 All tests shall be performed in the presence of and to the satisfaction of the Air Products representative. The Air Products representative shall receive 24 hours advance notice when any test is to be performed.
28.3.3 Due regard for safety shall be constantly observed.
28.3.4 Electrical Isolation Testing
28.3.5 After the pipeline is installed and sealed in the casing, but before it is connected to the main pipeline, an electrical resistance test shall be made between the pipeline and casing. The resistance must be 100,000 ohms or greater to be acceptable when measured with a Megger having a minimum test voltage of 500 Vdc. Failure to attain the specified resistance shall require dismantling, reassembling, and retesting the casing assembly or other corrective action to clear the fault by a method acceptable to the Air Products representative.
28.3.6 After backfilling, tests shall be made to ensure metallic pipelines are not shorted to the casing and all test station wiring is functioning properly. Pipe-to-casing resistance shall be 0.5 ohms minimum. Wire continuity shall be 0.0 ohms.
28.3.7 After the insulating flanges are installed, an electrical resistance test shall be made across each flange. The resistance must be greater than 0.5 ohms to be acceptable. In addition, each bolt of the insulated joint shall be checked with an ohm meter. Any bolt having a bolt-to-flange resistance reading of less than 300,000 ohms shall have its insulating sleeve and washers replaced and its resistance rechecked. This procedure shall be repeated until an acceptable resistance reading is achieved.
28.3.8 A report shall be prepared certifying that all casings, flanges, and test wires have been tested and meet the criteria required by preceding paragraphs 28.3.5, 28.3.6, and 28.3.7.
| Holiday Spark Testing – Underground Piping | ||||||
|
|
||||||
| Holiday Detector | ||||||
| Manufacturer | Project | |||||
| Type/Model | Location | |||||
| Voltage | Contractor | |||||
| Date | Line Number | From | To | |||
| Remarks | ||||||
| 1. Type of Protective Coating Used: | ||||||
| 2. Repairs Made: | ||||||
| Verification | ||||||
|
____________________________________ |
______________________________ |
|||||
| Air Products Superintendent | Contractor Superintendent | |||||
Form 7935 (Rev. May-12)
Figure 1 – Casing Details – Crossing Under Railroad or Roadway
Notes:
- When identified on the contract drawings, casings shall have one low point and one high point vent pipe as shown.
- Insulators and seals shall be as shown in Appendix A.
- Casing vent pipes shall be painted above grade according to 4WEQ-6804.
- Unless otherwise identified on the pipeline drawings and/or as determined by governing authority.
- Mitered weld joints are not acceptable.
Table 1
Casing Size and Wall Thickness
|
Pipeline Size mm (Inches) |
Casing
Size for Railroad mm (Inches) |
Casing
Size for Roadway mm (Inches) |
Minimum Wall Thickness for Railroad Casings
mm (Inches) |
Minimum Wall Thickness for Road Casings
mm (Inches) |
| 50 (2) | 150 (6) | 150 (6) | 5.0 (.188) | 6.4 (.250) |
| 75 (3) | 150 (6) | 150 (6) | 5.0 (.188) | 6.4 (.250) |
| 100 (4) | 200 (8) | 200 (8) | 5.0 (.188) | 6.4 (.250) |
| 200 (8) | 300 (12) | 300 (12) | 6.4 (.250) | 6.4 (.250) |
| 250 (10) | 400 (16) | 350 (14) | 7.2 (.281) | 6.4 (.250) |
| 300 (12) | 450 (18) | 400 (16) | 8.0 (.312) | 6.4 (.250) |
| 350 (14) | 500 (20) | 450 (18) | 8.8 (.344) | 8.0 (.312) |
| 400 (16) | 550 (22) | 500 (20) | 9.5 (.375) | 9.5 (.375) |
| 450 (18) | 600 (24) | 550 (22) | 10.4 (.407) | 10.4 (.407) |
| 500 (20) | 650 (26) | 600 (24) | 11.2 (.438) | 11.2 (.438) |
Appendix A
Miscellaneous Materials
| Item | Trade Name Or Model | Manufacturer And Home Office
|
| Casing End Seals
(Figure 1) |
Link-Seal Model Pl
(Preferred)
“Z” Seals
Model S |
Thundeline Corp.
Wayne, MI 48104
T.D. Williamson, Inc. Tulsa, OK 74101
PSI Industries, Inc. Burbank, CA 91504 |
| Casing Insulators
(Figure 1) |
Thinsulators M-2
Model PE |
T.D. Williamson, Inc.
Tulsa, OK 74101
PSI Industries, Inc. Burbank, CA 91504 |