Vacuum Jacketed Pipe Technical Specification | Installation | Manufacturers

1. PURPOSE

1.1       This engineering specification establishes the minimum design and performance requirements for vacuum jacketed pipe assemblies.

2. SCOPE

2.1       This specification applies to all vacuum jacketed pipe manufactured for Company for the purpose of transferring liquid or gaseous cryogenic fluids intended for non-ultrahigh purity services in the Continental United States and Canada.

3. RELATED DOCUMENTS

3.1      Company Engineering Documents

Oxygen Clean (Class AA) Inspection and Acceptance Requirements

Process Clean (Class B) Inspection and Acceptance Requirements

3.2      American Society of Mechanical Engineers (ASME)

Boiler and Pressure Vessel Code (BPVC)

Section VIII            Rules for Construction of Pressure Vessels

Section IX               Welding and Brazing Qualification

B31.3                     Process Piping

3.3      Compressed Gas Association (CGA)

341                        Specification for Insulated Cargo Tank for Nonflammable Cryogenic Liquids

3.4      International Code Council (ICC)

IBC                        International Building Code

4. GENERAL

4.1       All phases of fabrication and testing shall be made accessible to Company or a designated inspector, at reasonable times as Company may require.

4.2       The word “approved” as used herein means that the supplier shall submit to Company the described design, item, or procedure for written approval before use or fabrication.

4.3       The supplier, his facilities, personnel, equipment, and procedures shall be qualified (that is, certified, approved, authorized) when and as required by any of the aforementioned related documents and standards.

4.4          The supplier shall manufacture the unit to this specification and drawings and data sheets supplied by Company via the purchase order unless otherwise stated or arranged by

Company.

4.5         The supplier shall specify, in writing, any or all exceptions taken to this specification. Deviations from this specification shall be approved in writing by Company before implementation.

4.6         Units shall be inspected in accordance with the purchase order requirements.

5. DESIGN AND MANUFACTURING CRITERIA

5.1         General

5.1.1      The vacuum jacketed transfer pipe shall be designed to the Project Equipment Specification (PES) attached to this engineering specification if Company does not provide the supplier with detailed design drawings.

5.1.2      Heat Leak

5.1.2.1   The guaranteed heat leak for vacuum jacketed pipe, bayonets, and field joints shall not exceed the following values in liquid nitrogen service:

Vacuum Insulated Inner Pipe Nominal Size (in)	Heat Leak in BTU per Hour
	Pipe	Bayonet	Field Joint
1/2	0.35/ft.	10	6
1	0.50/ft.	14	7
1.5	0.60/ft.	16	9
2	0.80/ft.	21	12
3	1.0/ft.	29	30

5.1.3      Piping Stress Analysis

5.1.3.1   The mechanical integrity of vacuum jacketed piping shall be verified by a qualified stress engineer utilizing a recognized pipe stress analysis computer program, where applicable. Piping in the following categories shall be analyzed directly by Company Stress Engineering or under the direct control, review, and approval of Company Stress Engineering:

• All VJ piping between the nozzle on flat bottom storage tanks, up to and including the first automatic shutoff valve
• All VJ piping containing any flammable, lethal, or oxidizer fluid

5.1.3.2   All other VJ piping systems shall be stress-analyzed by a qualified stress engineer. The analysis may be done by the VJ supplier or their subcontractor at the discretion of the Company specifying engineer.

5.1.4      When isometric layout drawings are provided, all dimensions are for inner and outer lines at ambient 21.1°C (70°F) temperature.

5.1.5      The standard material for inner and outer line (except bellows) is 304 stainless steel. Other 300 series stainless steel materials are acceptable alternates.

Note:  The PES shall indicate when special materials are required for the inner lines such as Nickel 200 or Monel® 400 for strong oxidizer services such as fluorine.

5.1.6      Welding shall be in accordance with ASME B31.3 and shall be performed by welders who are qualified in accordance with ASME Code, Section IX.

5.1.7      Butt-weld fittings shall be used for fitting materials.

5.1.8      All expansion joints, flex hoses, spool welds, pumpout ports, getter capsules, bayonets, safety relief devices, insulated spool connections, valves, and other details on the outer jacket shall avoid interference with piping support locations [300 mm (12 in) minimum clearance on either side of support].

5.1.9      For shipment purposes, the transfer system shall be designed such that no stress shall exceed the lesser of 1/3 of the minimum ultimate tensile strength or 2/3 of minimum yield strength of the material used for the following requirements:

Weight (Individual Section)                     G-load Requirement

< 100 lbs                                                       8g

100 lbs < 1000 lbs                                          4g

> 1000 lbs                                                      2g

With Company’ approval, these g-load requirements may be relaxed if the supplier can demonstrate that no damage will occur to the equipment because of special shipping precautions taken by the supplier.

5.1.10    The supplier’s serial number shall be engraved or stamped on each spool along with its date of manufacture, its Maximum Allowable Working Pressure (MAWP), and the product for which it was initially intended.

5.1.11    When multiple spools are specified, the supplier shall choose spool lengths to produce the fewest number of shippable spools, while accounting for the additional space needed at the installation site for assembly. Shipping envelope limits shall be stated on the PES.

5.1.12    Supplier shall stagger field joints in lines running parallel to maintain a minimum edge-to- edge clearance between adjacent lines.

5.2         Inner Line

5.2.1      The design, manufacturing, inspection, and testing of the inner line shall be in accordance with ASME B31.3. The design pressure and temperature, the nominal line size, and any other considerations shall be specified in the PES.

5.2.2      The schedule and diameter of the inner line shall remain consistent throughout an individual transfer assembly unless otherwise specified by Company. The inner line wall thickness shall be a minimum of 1.65 mm (0.065 in) for inner line sizes greater than 19 mm (0.75 in) OD tube.

5.2.3      Inner line ends shall be butt-weld stubs, socket-weld couplings, or bayonets. For oxidizer service, bayonets are not allowed; only welded construction is permitted.

5.3         Outer Line

5.3.1      The outer line shall be designed to withstand 2 bar g (30 psig) minimum collapse pressure in accordance with CGA Pamphlet 341 or ASME Section VIII.

5.3.2      The outer line wall thickness shall be a minimum of Schedule 5S. The nominal diameter shall be sized such that it is adequate for insulation purposes.

5.3.3      The supplier shall recommend locations and design of supports for the outer jacket such that they are in accordance with ASME B31.3 for 110 mph wind loads exposure C and for an essential facility in a location with Ss=1.5 and S1=0.6 using International Building Code (IBC) methods, unless otherwise specified on the PES. PES to state which version of the IBC has been adopted by the local Authority Having Jurisdiction (AHJ).

5.3.4   All welds shall be full-penetration butt-welds, with the exception of end transition plates between inner and outer line and evacuated joint slip-on jackets that require fillet welds.

5.3.5   All outer jacket fittings shall be butt-welded. Mitered joints are acceptable where jacket loads are minimized and sufficient flexibility is provided using hoses and the bellows on the jacket.

Note: Mitered joints are not approved when anticipated cooling/warming cycles exceed 7000. This restriction will be noted on the PES.

5.3.6   When required by the PES, eccentric reducers shall be used to maintain the same bottom of pipe elevation where reductions occur in pipe.

5.4      Annulus

5.4.1   The inner line and laminar radiation shielding shall be supported by Micarta®, G-10 or G-11 epoxy reinforced fiberglass spacers or fiberglass reinforced Teflon spacers.

Note: Fiberglass reinforced Teflon is preferred in oxidizer service.

5.4.2   The spacing and design of these supports shall meet the requirements of ASME B31.3 for an essential facility in a location with Ss=1.5 and S1=0.6 with the inner pipe filled with a fluid of 1.38 specific gravity. International Building Code methods shall be used unless otherwise specified on the PES. PES to state which version of the IBC has been adopted by the local Authority Having Jurisdiction (AHJ).

5.4.3   The inner line shall be completely wrapped with one of the following:

• A minimum of 10 layers of fiberglass insulation paper alternating with aluminum foil.
• A minimum of 10 layers of aluminized Mylar crinkled to prevent layers from being in direct contact.

Use of tape to secure the shielding shall be minimized. The wrap density shall be between 55 layers per inch to 60 layers per inch.

5.4.4   Blanket wrapping is only permitted for line outside diameter equal to or greater than 48 mm (1.9 in) [corresponding to DN40 (NPS 1 1/2) pipe] when aluminum foil is used. Overlapping helical wrapping (like the stripe on a barber pole or candy cane) shall be used for all smaller lines and at elbows, tees, and flex lines.

5.4.5   All palladium oxide getter material shall be contained in a canister external to the outer jacket that communicates with the annular space, or in a totally enclosed sintered brass canister contained within the annular space. All other getter materials shall be contained in fiberglass insulating paper inside of fine copper mesh screen or embedded in sintered brass, or contained by a method proposed by the supplier and approved by Company.

Note:  This applies to all cryogenic services. In liquid oxygen service, oxygen can potentially leak from the inner line and react with the getter material. When getter material is outside of its container, and in contact with the wrapping material, oxygen exposure can lead to ignition and possible explosion of the wrapping material. Even in non-oxygen services, a leak in the external line can cause an enriched oxygen environment by condensing liquid air in the annular space.

5.4.6   The supplier shall not block the vacuum relief device or the evacuation port with the laminar radiation shielding, nor shall its installation impede vacuum pumping.

5.4.7   The annular space shall be evacuated while the inner line is heated to a minimum of 93°C (200°F) and a maximum of 149°C (300°F) for aluminum foil insulated lines or a maximum of 121°C (250°F) for aluminized mylar insulated lines. The evacuation shall continue with heating until the annular vacuum is below 10 microns. The heat may be discontinued at this point, but the line is to be evacuated below 2 microns before sealing. The cold vacuum shall be less than 1 micron.

5.4.8   Precaution shall be exercised not to damage or to reduce the effectiveness of the laminar radiation insulation during heating.

5.4.9   The vacuum pump system shall be equipped with a liquid nitrogen trap to prevent oil from entering the annulus during evacuation.

5.5      Flexible Line

5.5.1   Inner line expansion bellows and flexible hoses are only permitted when specified by Company on the PES.

5.5.2   Outer line bellows shall be 316L unless otherwise stated in the PES.

5.5.3   Outer line bellows may require a protective coating for environmental corrosion, such as salt atmosphere. The supplier shall obtain Company approval for any coating proposed. A stainless steel braid abrasion cover is required on the flexible section of the outer line to protect it from damage.

5.5.4   Only annular corrugated type seamless or butt-weld flexible sections shall be used.

5.5.5   Inner or outer line flexible hoses or expansion joints shall be designed for a recommended minimum number of 15,000 cycles. The design shall be according to recognized methods such as the “Standards of the Expansion Joint Manufacturers Association.” All inner line components shall be designed for a minimum pressure equal to the safety valve setting of the system. Outer line expansion joints shall be designed for a pressure range from 30 psig external pressure to a minimum positive pressure equal to the outer jacket relief valve setting, maximum thermal range difference between inner and outer line, and maximum expected operating cycles.

5.5.6   The specified design movements of any flexible component shall be a minimum of one and one-half times the calculated required movement of the flexible component. Normal movement of the bellows shall not exceed 50% of maximum rated movement.

5.5.7   Where vacuum jacketed flexible hose is used, the inner line shall have a burst pressure of four times design pressure.

5.6      Valves

5.6.1   All valves exposed to the cryogenic fluid temperature shall be extended stem and vacuum jacketed, unless otherwise indicated by Company on the PES.

5.6.2   Preferably, valves should be installed with the operator, or hand wheel, in a vertical position. Rotating the valve stem from vertical to a minimum of 15 degrees above horizontal is an acceptable alternative.

5.6.3   Valves shall not be installed in vertical pipe runs in continuous cryogenic service.

5.6.4   Company reserves the right to review valve types and sizes and make corrections if the valves are not specified by Company.

5.7      End Connection Options

5.7.1   End connections on vacuum jacketed piping spools are used to connect to other vacuum jacketed piping spools or to transition to non-vacuum jacketed piping. The end connection options are:

• Bayonet
• Butt-weld end or socket-weld coupling with VJ can (field evacuated)
• Butt-weld end or socket-weld coupling with urethane foam joint

Note:  Threaded end connections shall not be used.

5.7.2      Bayonets shall be suitable for horizontal and/or vertical (male pointing down) orientation. For flammables, solid flange bayonet shall be used, unless otherwise specified by Company.

5.7.3      Where joints are to be insulated with VJ cans in the field by others, the PES will indicate whether the supplier shall furnish all materials for the fabrication and installation of the cans, to include outer jacket, radiation shielding insulation, evacuation port, and relief valve for each field connection.

Note:  The outer jacket or “clamshell” shall be constructed of two separate pieces; it shall not be fabricated by scoring the outer jacket and bending it open and closed.

5.7.4      Where joints are to be insulated with urethane foam in the field by others, Company will furnish the foam insulation and the vapor barrier material, unless otherwise indicated on the PES. The standard insulation technique involves tapering the insulation material, so welded insulation standoff rings are not required, unless indicated on the PES.

5.8         Relief Devices and Accessories

5.8.1      If required by the PES, each spool section shall have a thermocouple gauge tube, such as a Hastings-Raydist Model DV6R, for vacuum monitoring.

5.8.1.1   The gauge tube shall be isolated from the annular space via a diaphragm or bellows-sealed packless isolation valve.

5.8.1.2   Supplier shall furnish a permanent, but removable, stainless steel cover for gauge assembly protection.

5.8.2      Each spool section shall have an evacuation port and a relief device located on the outer line. A single device serving both purposes may be provided.

5.8.3      The relief device included in the outer jacket of each spool shall prevent vacuum or pressure failure of the outer jacket. The device shall be constructed of all stainless steel (coated to prevent galling), or brass/stainless steel combination. The relief device shall be designed with a double or triple O-ring seal when the piping system is exposed to severe cyclic or vibrating service conditions.

5.8.4      Jacket relief devices using cylindrical plugs that can be ejected when relieving occurs shall be fitted with plug restraints or deflector shields to ensure personnel safety.

5.8.5      A thermal relief valve for the inner line shall be installed on the section of the transfer system in which product may be trapped, or as otherwise specified by Company. The preferred method is to attach vacuum jacketed “risers” to the inner line to which safety valves can be attached. The “risers” shall be positioned such that they are at a greater elevation than the outer line.

6. CLEANING AND TESTING

6.1         Cleaning

6.1.1      For oxygen service, the inner line shall be oxygen cleaned to meet the requirements of Oxygen Clean (Class AA) Inspection and Acceptance Requirements. For other services, the inner line shall be process cleaned to meet the requirements of 4WPI-SW70002 as a minimum.

6.1.2      The inner and outer line exposed to the annular space shall be process cleaned to meet the requirements of Process Clean (Class B) Inspection and Acceptance Requirements as a minimum.

6.1.3      The PES may specify additional cleaning requirements.

6.2      Testing

6.2.1   Not less than 5% of circumferential butt-welds shall be examined fully by random radiography or by random ultrasonic examination in accordance with ASME B31.3. The supplier shall provide detailed inspection procedures to Company for approval.

6.2.2   At its discretion, Company may exercise the option as stated in paragraph 7.3 and require that the supplier substantiate his heat leak claim on a random transfer assembly. Failure to meet the guaranteed heat leak values is cause for rejection. Company may notify the supplier of its intention to exercise this option at any time before shipment of the transfer assembly. If a deficient unit is discovered, Company reserves the right to order the test of another unit with no financial obligation.

6.2.3   The inner line shall be pneumatically or hydrostatically tested per ASME B31.3. Any indication of a leak is cause for rejection, repair, and re-testing.

6.2.4   Inner and outer line shall be leak tested using a Mass Spectrometer Leak Detector (MSLD) set on 1 x 10-9 to 10 x 10-9 scc/sec scale with the annular space under vacuum (less than 5 microns). The inner line shall be pressurized to the MAWP with helium gas or helium/nitrogen mixture (minimum of 10% helium) and all outer weld joints sprayed with helium gas. No leakage shall be indicated by the MSLD throughout the test.

6.2.5   With the annulus pressure equal to or less than 5 microns, a warm vacuum retention test shall be conducted for a minimum of 72 hours to a maximum of 168 hours. Readings of annulus pressure and outer line temperature shall be recorded at approximately 24-hour intervals. The same vacuum gauge and gauge tube shall be used through this test. The vacuum log shall be transmitted to Company for approval before shipment.

The minimum specified vacuum level acceptance criteria shall be:

• The vacuum level rises less than 2 microns (2.7 x 10-3 mbar) per day for two days followed by a no rise period with a final level of no more than 15 microns (20.3 x 10-3 mbar). A steady increase throughout the retention period is not acceptable and spools shall be rejected.
• Spools with vacuum levels between 15 and 30 microns (20.3 and 40.6 x 10-3 mbar) may be subjected to additional retention testing as well as cold shocking at the option of Company. Lines with a vacuum level of no more than 35 microns (47.3 x 10-3 mbar) after additional retention testing and showing an off-scale (pegged low) reading after one hour of being cold shocked with liquid nitrogen will be accepted.

6.2.6   A cold shock test, if required by Company, of the inner line using liquid nitrogen in conjunction with a MSLD having a helium sensitivity set on 1 x 10-9 to 10 x 10-9 scc/sec scale shall be performed. This test shall be conducted on the complete unit only after all the other required tests have been acceptably performed.

7. SUBMITTALS

7.1       The supplier shall certify in writing on his letterhead that the transfer system has been manufactured, designed, cleaned, inspected, and tested in accordance with all provisions of this specification, ASME B31.3, and the PES.

7.2       The supplier shall submit to Company for approval one copy of the transfer system detail drawings including valve details, bayonet details, and flexible line details.

7.3       The supplier shall submit to Company a procedure, a cost quotation, and a time schedule for a test to substantiate his heat leak claim for the transfer system.

7.4      The supplier shall submit to Company the following documents:

• Both predicted and guaranteed heat leak ratings for the system (to include pipe, bayonets, field joints, and flexible lines).
• Cool-down information.
• A recommended spare parts list for the vacuum jacketed transfer system.
• Drawings/cutsheets of all nonfabricated equipment.

7.5      The following is a list of further items that may be required for submittal by Company:

• Shop Drawings
• Material Certifications
• Fabrication and Testing Procedures

–    Welding details/procedures/inspection requirements

–    Cleaning

–    Pressure testing inner line

–    Vacuum testing

–    Additional Testing

• Maintenance Manuals and Instructions
• Design Calculations
• Radiographs

8. WARRANTY

8.1      The warranty shall be in accordance with the Terms and Conditions that form a part of Company’ purchase orders.

8.2       The supplier shall warrant that all equipment, components, and appurtenances supplied herewith are new, of recent manufacture, and first line quality, and have been supplied in accordance with this specification.

8.3       The supplier shall warrant that its equipment meets or exceeds the performance guarantees stated in the original cost quotation.

8.4       All parts, components, and accessories provided as part of the transfer system shall have a minimum of one-year warranty.

8.5       The warm vacuum of each spool shall not increase more than 10 microns above the final room temperature test reading (see paragraph 6.2.5) for a period of one year from the time of its delivery to Company.

8.6       When pre-approved in writing by the supplier, Company shall be permitted to perform warranty work at Company facilities. The supplier shall reimburse Company for such labor and material costs necessary to conduct these agreed upon repairs.

9. PACKING AND SHIPPING

9.1       All open pipe ends shall be wrapped with polyethylene sheets of 0.004″ minimum thickness and sealed with waterproof tape. A further covering should be applied to protect the integrity of the polyethylene during shipment.

9.2       The unit shall be packaged in a plywood crate and shall be adequately restrained within this crate via an appropriate packing material such as foam.

Note: Company has the option of waiving the requirement for crating when the supplier coordinates the shipment on a dedicated truckload, and takes responsibility for unit until arrival at the installation site.

9.3      Units shall be released for shipment in accordance with the purchase order requirements.

9.4       All acceptance tests and inspections required by this specification shall be completed before shipment, unless a written waiver has been issued.

9.5       For multi-spool vacuum jacketed line system, the supplier is required to match mark each spool end for ease of field installation.

Recommended Content of the Project Equipment Specification (PES)

A1.      PURPOSE

A2.      SCOPE

• Company provided description of VJ system.
• Company provided project-specific documents and drawings such as isometric layout.
• Piping stress analysis (indicate whether this is Company’ or supplier’s scope).
• Valves, filters, flow elements, pumpouts, and other accessories (indicate whether these items, if any, will be specified and/or supplied by Company).
• Vacuum cans (indicate supplier scope in providing vacuum cans at joints between piping spools).
• Insulation rings, urethane foam, vapor barrier (insulation rings are not normally required and the foam and vapor barrier are normally Company’ scope).

A3.      RELATED DOCUMENTS

A4.      DESIGN DATA

• Piping layout (normally provide in an isometric drawing by Company)
• Locations of valves and/or thermal relief devices
• Pipe supports (location and type normally provided by Company)
• Line number
• Design pressure
• Design temperature
• Process fluid
• Inner line size (nominal)
• Shipping envelope limits
• Wind and seismic requirements
• Acceptability of expansion bellows and flexible hoses on the inner line (yes/no)
• Outer line expansion bellows material (if other than 316L)
• Anticipated number of cooling/warming cycles (mitered joints shall not be used above 7000 cycles)

• Severe cyclic or vibrating service requiring double/triple O-ring seal on relief devices      (yes/no)

• Requirement for eccentric reducers to maintain the same bottom of pipe elevation    (yes/no)

• Special cleaning requirements (if any)

A5.      END CONNECTION

• Size and schedule of butt-weld ends
• Size and pressure class of socket-weld couplings
• Acceptability of bayonet connections (yes/no)
• Joint insulation (indicate vacuum can, urethane foam joint, or other)

A6.      ACCESSORIES

• Requirement for thermocouple gauges with isolation valves (yes/no)
• Requirement for special tools (operator) for field evacuation (yes/no)
• Spare parts

A7.      TESTING DATA

• Length (hours) of vacuum retention test
• Requirement for cold-shock test (yes/no)

A8.      REQUIRED SUPPLIER DOCUMENTATION