Hot Tapping GPL 03-01-04 FEBRUARY 2003
MASTER SPECIFICATION Mobil Producing Nigeria Unlimited
GPL 03-01-04
Hot Tapping
FEBRUARY 2003
Table of Contents Table of Figures .............................................................................................................................3 1.
Required References ............................................................................................................4 1.1. 1.2. 1.3. 1.4.
2.
Safety Precautions .................................................................................................................5 2.1. 2.2.
3.
MPN Master Specifications ......................................................................................4 API–American Petroleum Institute ........................................................................4 ASME–American Society of Mechanical Engineers .............................................5 NFPA–National Fire Protection Association..........................................................5
Restrictions ................................................................................................................5 Piping and Storage Tanks ........................................................................................6
Procedures.............................................................................................................................7 3.1. 3.2. 3.3. 3.4. 3.5. 3.6. 3.7. 3.8.
Design Considerations and Inspection....................................................................7 Hot Tap Preparation.................................................................................................9 Welding ....................................................................................................................10 Weld Inspection and Testing..................................................................................11 Hot Tap Assembly Testing .....................................................................................12 Coupon Cutting .......................................................................................................12 Blinding a Stopple Fitting ......................................................................................13 Replacing a Pipe Section ........................................................................................14
Appendix: Hot Tap Checklists ..................................................................................................17 1.
Checklists .............................................................................................................................17 1.1. 1.2. 1.3. 1.4.
Before Starting a Hot Tap......................................................................................17 Before Welding ........................................................................................................19 Before Cutting .........................................................................................................19 Before Removing the Tapping Machine ...............................................................20
Attachment: Purpose Codes Definitions ...................................................................................21 REVISION LOG SHEET............................................................................................................22
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Table of Figures Figure 1: Arrangement for Making Hot Tap Showing Tapping Machine in Position.........13 Figure 2: Method of Removing the Gate Valve Used for the Hot Tap..................................14 Figure 3: Hot Tap Application Involving the Removal of a Section of Pipe .........................15
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Scope 1) This specification covers hot tap procedures for piping and storage tanks in the following locations: a) Petroleum refineries b) Chemical plants c) Pipelines d) Onshore and offshore production e) Processing facilities f) Similar installations This specification applies to piping and storage tanks that are fabricated only from ferritic or austenitic steel materials. 2) Hot taps are not permitted on materials that require postweld heat treatment (PWHT). 3) Hot taps on other materials may require special procedures and shall be approved by Company Designee on an individual, case by case basis.
1.
Required References This Section lists Practices and Standards that are generically referenced and assumed to be a part of this document. Unless otherwise specified herein, use the latest edition. 1.1.
1.2.
MPN Master Specifications GPL 03-01-01
Piping General Design
GPL 03-20-01
Piping Material Classes
MPL 16-P-40
Piping Fabrication, Erection, Inspection, Cleaning and Testing
GPL 18-07-01
Welding Procedures
API–American Petroleum Institute API RP 2201
Procedures for Welding or Hot Tapping on Equipment in Service
API STD 620
Design and Construction of Large, Welded, Low-Pressure Storage Tanks Ninth Edition; Addendum 1-December 1996; Additional Pages for Addendum 1-February 1997; Addendum 2-December 1997; Addendum 3-December 1998
API STD 650
Welded Steel Tanks for Oil Storage Tenth Edition; Addendum 1 March 2000
API STD 653
Tank Inspection, Repair, Alteration, and Reconstruction Second Edition; Errata February 1996; Errata May 1996; Follow up to Errata May 1996; Addendum 1-December 1996; Addendum 2 December 1997; Addendum 3 December 1998; Addendum 4 December 1999
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1.3.
1.4.
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ASME–American Society of Mechanical Engineers ASME B31.3
Process Piping
ASME B31.4
Pipeline Transportation Systems for Liquid Hydrocarbons and other Liquids
ASME B31.8
Gas Transmission and Distribution Piping Systems
ASME SEC IX INTRODUCTI ON
BPVC SECTION IX Welding and Brazing Qualifications Non-Interfiled (Boiler and Pressure Vessel Codes)
NFPA–National Fire Protection Association NFPA FPH Storage of Flammable and Combustible Liquids SECTION 3-21
2.
Safety Precautions 1) Hot tap operations shall be well coordinated among the Engineering, Maintenance, and or following groups: a) Hot Tap Contractor b) Inspection Personnel c) Loss Prevention Personnel Only qualified Personnel shall perform hot tap operations. 2) Each tap made on the system under pressure shall be performed by a crew qualified to make hot taps. No hot taps shall be performed until appropriate calculations of allowable internal pressure during the tapping process have been made. This is especially important when considering tapping high strength steel lines such as X-42 or X-60 grade pipe. 3) A comprehensive overall job plan shall be prepared by Contractor. 4) The bell hole shall be of such a size as to provide 3 ft (0.91M) clearance on each side of the tapping machine. If a horizontal tap is being made, there shall be 7 ft (2.13M) of clearance beyond the end of the tapping machine. 5) The bell hole shall have a sloping side with steps. 6) The hot tap valve shall be tested before making the tap, and the packing of all working parts of the tapping machine shall be inspected before starting the tap. 2.1.
Restrictions A hot tap shall not be made on: 1) Piping and storage tanks that contain a flammable gas and air mixture 2) Piping and storage tanks that contain acids, ammonia, chlorine, or chlorine compounds which could decompose from the heat of welding 3) Piping and storage tanks that contain hydrogen above 100°C (212°F)
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4) Piping and storage tanks that are clad, lined, or overlaid with any of the following: a) Glass b) Lead c) Refractory d) Cement e) Plastic or alloy metal 5) Piping and storage tanks that are jacketed 6) Piping and storage tanks that require PWHT according to applicable codes, standards, and/or Global Practices 7) Piping and storage tanks in hydrofluoric acid service 8) Piping and storage tanks in caustic service where concentration and temperature require PWHT, or where steam-out of caustic lines/equipment is performed during shutdowns/start-ups—Regardless of concentration, hot taps in caustic lines shall be temporary, pending PWHT or replacement during the maintenance outage. 9) All air- lines where lubricating oil may have entered the system, resulting in a hazardous atmosphere 10) Pressure vessels and heat exchangers 2.2.
Piping and Storage Tanks 2.2.1.
General 1) Hot tapping on piping and storage tanks in amine, acids (such as HF Acid), and sour gas services shall not be performed without consulting a Materials Engineer or Company Designee. 2) The operating pressure and temperature of piping/storage tanks to be hot tapped shall at no time exceed the rated pressure and temperature of the tapping or stopple plugging machines. 3) When making a hot tap on a line, verify that the correct line is being tapped. In the case of an underground line, verify that a sleeve is not being tapped rather than the pipe.
2.2.2.
Flow and Velocity 1) Flow in lines shall be maintained during welding operations to reduce heat accumulation. 2) Avoid high flowrates when welding to prevent excessively rapid cooling of the welded area. 3) A minimum velocity of 0.4 m/s (1.3 ft/s) is recommended in gas lines. 4) The contents of storage tanks shall not be circulated during hot tapping. a) Tank inlet and outlet valves shall be closed and locked shut. b) Mechanical mixers shall be locked out and heating coils shut off and locked shut.
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c) There shall be a 1 m (3 ft) minimum liquid level above the highest weld on the hot tap connection reinforcing pad. 2.2.3.
Health, Safety, and Environmental 1) Hot tapping in the vapor space of a tank is permissible only when an inert gas blanket is maintained. Even then, frequent testing shall ensure that the gas in the vapor space is at no time in the flammable and/or explosive range. 2) In certain cases, such as in a flare line, there may be insufficient or interrupted flow that may result in a flammable mixture during the welding operation. a) In such cases, continuously purge the line with steam or inert gas. b) When hot tapping is performed on piping/storage tanks under vacuum, a continuous purge with an inert gas at 4 mm to 6 mm Hg (2 in. to 3 in. H2 O) shall be maintained during the hot tap to ensure an air-free operation.
3.
Procedures The hot tap procedures for piping and storage tanks shall be according to requirements of this specification, unless superceded by more stringent local regulations. It shall be authorized under company Management of Change Procedure or an equivalent procedure. 3.1.
Design Considerations and Inspection From records or stampings, determine the specification and suitability of the material to which the hot tap connection is being attached. Design of piping hot tap connections shall be according to ASME B31.3, ASME B31.4 or ASME B31.8, whichever is applicable. Design of tank hot tap connections shall be according to the applicable tank standard, for example API STD 620 or API STD 650. 3.1.1.
Calculations Calculations to determine the required thicknesses for piping/storage tanks, nozzle necks or fittings, reinforcing pads, and weld attachments shall take the following into account: 1) The design temperature and pressure of the existing piping or storage tank 2) Possible upset conditions that exceed the design conditions, which may occur during the hot tap operation or during welding 3) The required corrosion allowance 4) External differential pressure applied to the existing piping/storage tanks during testing of the hot tap fitting 5) The loads applied by the tapping equipment
3.1.2.
Hot Tap Connections Hot tap connections for piping additions shall be designed to accommodate the loads exerted by the new piping, including pipe movement.
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Hot tap connections and reinforcing pads (if required) shall be no less than 75 mm (3 in.) from a welded seam (weld-toe to weld-toe). Hot tap connections shall be at 90 degrees to the pipe, except 45 degree connections may be made into flare lines provided the following is true: 1) Design calculations are made for the connection to determine the extent of reinforcement needed 2) The weights of the valve and tapping assembly are considered 3.1.3.
Fitting Types 1) The acceptable types of hot tap fittings include both the weld-on type and bolt-on (mechanical) type. The weld-on type shall be used, except for lines where welding is not permitted or on lines requiring PWHT. The mechanical type shall be considered temporary and shall be replaced at the next planned shutdown. 2) The mechanical type consists of a split-sleeve bolted around the pipe. Packing and gaskets are required, and they shall be suitable for the temperature and fluid service. 3) The weld-on type fittings consist of the full encirclement split-tee type, as well as other types of weld-on branch connections as permitted in GPL 0320-01. 4) Full encirclement split tees, available from companies such as T.D. Williamson and IPSCO (International Piping Services Company), are required for full size hot taps and line stopple connections. This type of fitting is also recommended for one line size reducing taps. 5) Pipe-to-pipe reinforced (or unreinforced) connections and branch outlet fittings (O-lets) are preferred in steam and corrosive services. Full size connections are not recommended. If process conditions require a full size connection, the fitting shall be replaced at the next planned shutdown.
3.1.4.
Cutter Considerations Ascertain that the nozzle length plus the isolating valve length and thicknesses of the gaskets does not exceed the maximum travel of the cutter. Specify the cutter size that is required to: 1) Avoid interference with the weld areas and the inside diameter of the hot tap connection 2) Minimize the inside "lip," which may cause excessive turbulence near the piping/storage tank-to-nozzle junction area
3.1.5.
Other Considerations 1) Potential problems with metal cuttings contaminating the product stream shall be considered. 2) When tapping a line, the preferred location is on top of the pipe, so that metal cuttings will fall into the pipe and be washed away.
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3) Avoid hot tapping upstream of control valves, instruments, and rotating equipment unless filters or traps protect such equipment. 4) Verify that the tapping machine (including packing and elastomers) will not be affected adversely by the fluid in the piping/storage tank. 3.1.6.
Block Valve A full port gate or ball valve shall be used as a block valve for the tapping machine. 1) The valve shall be of adequate pressure rating for the intended service and shall be shop pressure tested (shell) and leak tested (seat/closure) prior to the installation. The valve pressure – temperature rating shall not be less then that of the existing piping system. 2) When the valve is to be left in place after completion of the hot tap, the following shall be suitable for the intended service, pressure, and temperature: a) Valve body b) Trim c) Packing materials
3.1.7.
Minimum Thickness of Wall Inspect and test the condition of the piping/storage tanks prior to hot tapping. By ultrasonic testing, ensure that the pipe or tank wall is free from laminations and that the thickness is adequate for safe welding. The minimum thickness depends upon the following: 1) The material being welded 2) The operating temperature and pressure during welding 3) The welding procedure 4) The product inside the pipe or storage tank Generally, the thickness shall be no less than 5 mm (0.20 in.) and at least the thickness calculated according to Section 3.1.1 for the hot and corroded condition.
3.2.
Hot Tap Preparation Prior to hot work, the following procedure is recommended: 1) Develop a detailed plan to clarify all concerns applicable to the hot tap. 2) Submit a detailed Safety plan for the hot tap operation including for all isolations. 3) Prepare engineering drawings that detail the hot tap operation. 4) Hold a coordination meeting with the Engineering, Maintenance, and or following groups: a) Hot Tap Contractor b) Inspection Personnel c) Loss Prevention Personnel
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5) Verify the correct piping/storage tank to be hot tapped, as well as the correct location. 6) Verify that the condition, material, and the measured thicknesses of the piping/storage tank to be hot tapped are adequate for welding. 7) Verify that the proposed welding procedure is suitable for the intended hot tap application. 8) Conduct all necessary hydrocarbon and oxygen tests to ensure that no flammable vapor is present. 9) Obtain a hot work permit. 10) Establish a fire watch and provide at least a 12 kg (30 lb) dry chemical extinguisher. 11) Complete the Hot Tap Checklist (refer to Appendix). 3.3.
Welding 1) The welding procedure to be used and the welders and welding operators shall be qualified according to the specific vessel, piping or pipeline code classifications. The welding procedures shall be submitted for Company Designee approval prior to mobilization. 2) Low-hydrogen rods with a minimum tensile strength of 480 MPa (70,000 psi) shall be used for hot tap welding on carbon steel piping or storage tanks. a) To minimize the risk of burn-through, it is recommended that the first weld pass shall be made with a 2.4 mm (3 /32 in.) diameter electrode. b) Subsequent passes shall be made with an electrode that is 3.2 mm (1 /8 in.) in diameter or less. c) Use welding parameters toward the lower end of the range that is recommended by Electrode Manufacturers. 3) When the temperature of piping/storage tanks being welded is below 10°C (50°F), the metal shall be kept warm (at 38°C to 93°C [100°F to 200°F]) during the welding operation in order to avoid cold cracking. a) Careful control of the metal temperature may be maintained by the use of thermocouples, if necessary. b) Welding on refrigerated piping/storage tanks shall be reviewed by the local plant engineering department or Company Designee. 4) When welding on piping and storage tanks that contain materials in the vapor phase, time shall be allowed between each weld pass to allow the parent metal to cool. 5) When welding on carbon steel or low alloy lines that have been infused with hydrogen atoms, allow a minimum of 24 hours after welding before doing NDE to allow for delayed cracking. 3.3.1.
Piping/Tanks Containing Hydrogen For piping/storage tanks that contain hydrogen, a hot tap is permitted only when the fluid temperature does not exceed 100°C (212°F). 1) Check piping/storage tank temperature with a magnetic surface thermometer immediately before welding.
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2) Restrict the interpass temperature to 149°C (300°F) maximum. 3.3.2.
Weld-On Fittings Before welding, the fitting shall be checked to ascertain that it is properly positioned to prevent misalignment of the tapping machine when the cut is made. For cuts at an angle other than 90 degrees, a drill pilot guide sleeve shall be welded to the part being tapped. The fitting shall be welded in place using the specified welding electrode classification, required number and placement of passes and use of the correct welding procedure. 1) Welding on piping shall be according to MPL 16-P-40 and the relevant codes and standards. Weld Procedures shall be qualified in accordance with GPL 18-07-01. 2) Any weld made on the inside of fittings shall be ground smooth to permit free passage of the cutter.
3.4.
Weld Inspection and Testing The welded attachment shall be inspected during and after welding, and shall be pressure tested before installing the tapping machine as follows: 1) The root pass and final pass of all welds shall be dye penetrant or magnetic particle inspected, the completed weld joint shall be 100% examined using ultrasonics and radiography to assure that the quality of welds meets the requirements of the applicable code acceptance criteria. 2) Connections shall be hydrostatically or pneumatically tested prior to cutting the coupon. a) The test pressure and duration shall be as required by the applicable code. b) If calculations show that the test pressure required by the code may cause local yielding, the test pressure may be reduced to the maximum pressure that will not result in stresses exceeding the yield strength at test temperature. c) The test pressure shall be at least equal to the maximum operating pressure of the hot tapped piping/storage tank, and shall not exceed the pressure ratings of the isolating valve and tapping machine. 3) The test fluid may be one of the following, depending on line temperature and test pressure: a) b) c) d)
Water Air Nitrogen Oil
If oil is used for a pressure test, it shall never be used above its auto-ignition temperature. 4) When air, nitrogen, or water is used and consequently heated, the pressure shall not be permitted to exceed the test pressure required by the governing code or standard. 5) When reinforcing pads are used, they shall be tested according to MPL 16-P-40.
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Hot Tap Assembly Testing The operability of the tapping machine shall be checked prior to use. After installation of the tapping machine, do the following: 1) Check the tightness of bolts, packing, and packing nuts. 2) Pressure test the assembly a) The test medium shall be the same as in Section 3.4. b) The test pressure shall be at least equal to the operating pressure of the piping being hot tapped.
3.6.
Coupon Cutting 1) The tapping machine shall be installed on the gate valve, as shown in Figure 1. a) The cutter shall be extended through the valve opening several times to be sure that it will clear. b) The operator shall ensure that there is sufficient clearance between the tip of the pilot drill and the trim of the closed valve to permit retraction of the cutter after the coupon is cut. c) When tapping a line, the operator shall determine the cutter travel required for cutting through the pipe wall without scoring the opposite side. d) The positions of the cutter (when fully retracted and after cutting through the pipe wall) shall be marked on the measurement rod of the tapping machine before drilling and documented for records. 2) When the pilot drill penetrates the piping/storage tanks, allow the product to fill the cutter housing and to bleed out through the vent valve on the tapping machine, except for products that are health hazard or highly volatile. Then close the vent valve. When the cutter penetrates the wall, run the machine a few turns to remove burrs. 3) The cutter and coupon shall be retracted, the valve closed, and the vent on the tapping machine opened. 4) With removal of the tapping machine, the connection is ready for use. 3.6.1.
Oil The cutter body may be filled with oil. 1) This will lubricate the cutter, absorb heat, and eliminate the air space. 2) Where contamination of product is a problem, the tapping machine body may be filled with the product if it is a Class II or Class III liquid, as classified in NFPA FPH SECTION 3-21. Oil shall never be used when tapping air lines.
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Figure 1: Arrangement for Making Hot Tap Showing Tapping Machine in Position DRILLING MACHINE
DRIVE SHAFT FOR HAND OR POWER OPERATION
OIL RESERVOIR
ADAPTER FOR DRILLING MACHINE
CUTTER
FULL-OPENING GATE VALVE
PILOT DRILL WITH COUPON-RETRIEVING PIN NEW BRANCH CONNECTION COUPON EXISTING PIPE HEADER
NOTE: If valve is to be removed after coupon is cut, a Lock-O-Ring fitting must be welded to header.
3.7.
Blinding a Stopple Fitting When it is desirable to remove the hot tap valve and to blind the hot tapped connection, the following procedure shall be used: 1) Weld a fitting complete with a T.D. Williamson Lock-O-Ring flange or an approved equivalent (refer to Figure 2) on the piping or storage tank being hot tapped. For small connections (NPS 2 and 3), a threaded plug and internally threaded flange shall be used.
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Figure 2: Method of Removing the Gate Valve Used for the Hot Tap
LOCKING RING SEGMENT O-RING SEAL
GATE VALVE FLANGE LOCKING RING SCREW
LOCK-O-RING FLANGE
LOCK-O-RING PLUG
2) Install the steel gate valve, adapter, and tapping machine. After cutting the coupon, remove the tapping machine, then remove the cutter from the tapping machine boring bar and attach a Lock-O-Ring plug or approved equivalent. 3) Re-install the tapping machine on the gate valve flange. a) Open the gate valve, and insert the Lock-O-Ring plug into the lock ring flange by extending the boring bar. b) Seal the plug by tightening the lock ring segments. c) Open the vent valve on the tapping machine to test the seal. The Buna-N O-ring seal material limits the use of standard seal plugs to temperatures that do not exceed 82°C (180°F). 4) Release the tapping machine from the plug and retract the cutter, leaving the plug holding the line pressure. 5) Remove the tapping machine and gate valve and attach a blind flange with proper gasket and bolting to the Lock-O-Ring flange. 3.8.
Replacing a Pipe Section When replacing or removing a pipe section, the procedures in Sections 3.1 through 3.7 shall be followed in installing a temporary bypass to permit work on the pipe section without interrupting flow (refer to Figure 3).
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1) The bypass may be smaller than line size and a flow calculation can be made to determine the minimum permissible size. 2) This method is usually limited to lines operating at temperatures not exceeding 82°C (180°F) because of the elastomeric sealing element of the stopple.
Figure 3: Hot Tap Application Involving the Removal of a Section of Pipe TEMPORARY BYPASS CONNECTION
TEMPORARY BYPASS CONNECTION SECTION TO BE REPLACED
STOPPLE CONNECTION
STEP 1
STOPPLE CONNECTION
TEMPORART BYPASS
LINE STOPPLE
LINE STOPPLE See Paragraph 5.5 for Stopple.
STEP 2 1. Remove bypass and install Lock-O-Ring plug. 2. Remove valve and install blind.
1. Remove bypass and install Lock-O-Ring plug. 2. Remove valve and install blind.
NEW SECTION TO PIPE
STEP 3 1. Remove stopple and install Lock-O-Ring plug. 1. Remove stopple and install Lock-O-Ring plug. 2. Remove valve and install blind. 2. Remove valve and install blind.
3.8.1.
Typical Hot Tap Procedure for Replacement The following is the typical hot tap procedure for the replacement of a pipe section: 1) A stopple fitting with a Lock-O-Ring or approved equivalent flange is welded on each end of the section to be isolated.
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2) Bypass fittings with Lock-O-Ring or approved equivalent flanges and equalization connections are welded to the line. (The equalization connections shall also be used for venting, purging, and testing purposes.) 3) At each fitting, the following shall occur: a) An isolating valve and a tapping machine are installed b) A tap is made through the valve into the line 4) The cutter is withdrawn after each tap, the valve is closed, and the tapping machine is removed. 5) The bypass line is installed, and the bypass valves are opened. 6) The seals of the stopple plugging machines shall be inspected for defects before installing the machines. The outside diameter of the sealing element must be correct for the inside diameter of the line to be hot tapped. 7) Stopple plugging machines are mounted on stopple fittings, and the plugging heads are lowered into sealing position. 8) The isolated section is vented, drained, and purged with an inert gas during cutting operations to remove this section. 9) The new pipe section is then welded to the line under continuous purge. a) The pressure is equalized. b) The plugging heads are retracted. c) The valves at the stopple connections are closed. d) The plugging machines are removed. 10) The bypass valves are closed, and the bypass line is removed. 11) Lock-O-Ring or approved equivalent plugs are installed in the stopple and bypass fittings with a tapping machine. 12) All equipment is then removed, the valves are recovered, and blind flanges are installed at stopple and bypass fittings. 3.8.2.
Liquid Service Lines In liquid service, lines to be removed shall be drained by drilling a drain hole on the bottom at one end that is to be cut and a vent hole on the top at the opposite end, after the stopple is in place.
3.8.3.
Flammable Materials Hot work can proceed only if the readings of flammable gases are below safe limits. Otherwise, the purge shall be continuous. 1) If the pipes contain flammable gas or liquid, the unwanted sections of pipe shall be purged with inert gas or steam, and a flammable gas check shall be done before cutting. 2) Cold cutting methods shall be used.
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Appendix: Hot Tap Checklists
1.
Checklists This checklist shall be attached to the Safety Permit prior to the start of hot tap work. Initial each item to indicate consideration has been given. Particular circumstances of the job may dictate additional checklist items.
Location:
Permit Issuer:
Date:
Contractor:
Brief Description: 1.1.
Before Starting a Hot Tap
Yes/ Initials No/ N/A Is hot tapping the most appropriate option? Have other alternatives (for example, next turnaround, piping/storage tank shutdown or isolation) been considered? Has the approved hot work permit been obtained? Has the coordination meeting between all involved departments been held? Has the equipment or line been checked to ensure that the materials and the services permit hot tapping? (Do not weld/braze on cast iron lines, except possibly for lowpressure water lines. Use mechanical fittings instead.) Has the exact location of the hot tap on the piping/storage tank been identified and marked? Has the area to be welded been inspected and the absence of laminations or other metallurgical imperfections verified? Are the thickness readings above the minimum recommended thickness? Is the selected welding procedure suitable for the intended hot tap application and approved? Has the metallurgy of the line or storage tank been established, and is it compatible with the connecting fitting? Have combustible and toxic gas tests been conducted in the area of hot tapping, and is there provision for continuous testing during the entire hot tap operation? Have engineering drawing(s) been prepared that detail the hot tap operation?
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Yes/ Initials No/ N/A Do the connections, reinforcing pads (if required), flanges, bolts, gaskets, and valve to be installed meet the piping code for the line or storage tank to be hot tapped? Is the gate valve full port? Has it been pressure tested? Does the tapping machine have suitable pressure rating, temperature rating, and adequate cutter travel for this job? Is there sufficient external clearance to accommodate the operation of the tapping machine? Is there adequate access and clearance to rotate the isolating valve if a threaded valve is used (e.g., for a corrosion probe fitting installation)? Is there sufficient internal clearance to retract the cutter through the valve? Is the hot tap fitting of the proper length to accommodate operation of the tapping machine? Is the material in the line stable under heated conditions and free of oxygen? Has suitable protective equipment been provided for all Personnel involved in the hot tap operation? Is a fire watch provided? Has adequate fire-fighting equipment been provided? Is the area to be hot tapped located 1 m (3 ft) below the liquid level of a tank or on a line in which fluid flow has been established? Is there adequate hoisting and support equipment for the tapping machine, and room for operational and emergency access? Is the work area protected from unauthorized entry during the hot tap operation? Has a procedure to isolate the work area in the event of an emergency been prepared, and are the Personnel involved trained to implement this procedure? Are there at least two egress/access areas provided if work is from a permanent or temporary platform?
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Before Welding Each of the following considerations shall be satisfied before welding:
Yes/ No/ N/A
Initials
Is a preheat of the weld area required? Is the fitting properly positioned so misalignment of the tapping machine will not occur? Have the flowrate, pressure, and temperature of the contained material been reduced as much as the process operations will allow? Is there liquid or flowing gas in contact with the area to be hot tapped? 1.3.
Before Cutting Each of the following considerations shall be satisfied before cutting:
Yes/ No/ N/A
Initials
Has the nozzle weld been examined for cracks and pressure tested? Has the nozzle reinforcing pad, if required, been pressure tested? Has the tapping machine assembly been pressure tested? Has the bleedoff valve been checked to be sure it will hold pressure, is operable, and is not obstructed? Are all bolts tight on the cutter and pilot bit? Is the coupon catcher on the pilot bit? Is the valve centered on the flange? Has the cutting depth been calculated to avoid cutting the opposite side of the pipe? Has the boring bar been run through the valve to ensure free passage? Have precautions been taken for safe disposal of material collected above the gate valve?
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Before Removing the Tapping Machine Each of the following considerations shall be satisfied before removing the tapping machine:
Yes/ No/ N/A
Initials
Have the Manufacturer's instructions been followed to be sure the boring bar is fully retracted before closing the isolating valve? Has the isolating valve been closed? Has the bleedoff valve been opened? Has all pressure been bled off the tapping machine before removing bolts from the flange?
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Attachment: Purpose Codes Definitions Code
Definition
C
Assigned to paragraphs containing specifications whose primary purpose is reduced costs. Reduced cost in this context refers to initial investment cost, and does not include Life Cycle cost considerations. Life Cycle considerations are captured under reliability, maintainability or operability purpose codes.
E
Assigned to paragraphs containing specifications whose primary purpose is driven by environmental considerations. Environmental considerations typically include specifications intended to protect against emissions/leakage to the air, water and/or soil. Deviations from the specifications contained in such paragraphs require formal review and approval according to local environmental policy.
I
Assigned to paragraphs that provide only clarifying information such as Scope statements, definitions of terms, etc.
M
Assigned to paragraphs containing specifications whose primary purpose is to provide for maintainability of equipment or systems. Maintainability provisions are those that facilitate the performance of maintenance on equipment/systems either during downtimes or during on-stream operations.
O
Assigned to paragraphs containing specifications whose primary purpose is to assure operability of equipment or systems. Operability is the ability of the equipment/system to perform satisfactorily even though conditions are off-design, such as during start-ups, process swings, subcomponent malfunction, etc.
R
Assigned to paragraphs containing specifications whose primary purpose is to improve or assure the reliability of equipment or systems. Reliability is a measure of the ability of equipment/systems to operate without malfunction or failure between planned maintenance interventions.
S
Assigned to paragraphs containing specifications whose primary purpose is avoidance of personnel or operational safety incidents. Any deviation from the specifications contained in such designated paragraphs requires formal review and approval according to local safety policy. Personnel Safety:
Refers to the avoidance of recordable personnel injuries, i.e. burns, cuts, abrasions, inhalation or exposure to dangerous substances, etc., that could result in medical treatment, restricted work, lost-time incidents or fatalities.
Operational Safety:
Refers to the prevention and control of process releases, fires, explosions, etc.
GPL 03-01-04 Feb03
MPN Projects Department
Page 21 of 22
GPL 03-01-04
Hot Tapping
FEBRUARY 2003
REVISION LOG SHEET
DATE
DESCRIPTION
ORIGIN
CHECKED
APPROVED
27 FEB 2003
Format change
Prem Pereira
Dan Pace
Garry Zirkle
GPL 03-01-04 Feb03
MPN Projects Department
Page 22 of 22
