1. PURPOSE
1.1 This global engineering specification defines the proper procedures for sealing shop-fabricated cold boxes for shipment over land and/or sea.
2. SCOPE
2.1 This specification applies to all shop-fabricated cold boxes, including circular cans, that have the potential to be exposed to rain, salt water, and/or salt-laden air during shipment. It does not apply to vacuum-jacketed boxes.
2.2 For all cold boxes (uninsulated, insulated, or partially insulated) this specification defines the procedures to minimize the entrance of moisture into the cold box structure. This moisture can cause internal or external corrosion of the vessels, piping, supports, and/or the interior of the cold box frame steel.
2.3 Other methods of sealing may be used with the prior approval by Air Products cold box engineering.
3. RELATED DOCUMENTS
3.1 Air Products Engineering Documents Painting and Corrosion Protection of New Construction for Design Temperatures to 649°C (1200°F) Cold Box Penetrations Standard Details
4. STRATEGY
4.1 Cold boxes shall be designed to be weatherproof and waterproof for outdoor operation. Before operation, but after the cold box shop fabrication is completed, there are many items that must be removed because of shipment clearance limitations, thus leaving openings in the box panels that must be sealed. In addition, there are other miscellaneous openings that must be sealed against water intrusion. All open ends of process lines must also be sealed. The amount and the extent of sealing required shall be as specified in the project-specific documents. It will be based on the project’s location, the method and duration of shipment, and the length of anticipated outdoor storage at the project site before operation.
5. SEALING PROCESS LINES
5.1 All open ends of process lines shall be sealed using the methods described in paragraphs 5.2 or 5.3 as specified in the project-specific documents.
5.2 Process Seal “S”: All process line open ends (interior and/or exterior) shall be covered with a plastic or metal cap and taped in place so that the entire system is closed to the atmosphere. In addition, the guidelines for “SS” sealing specified in paragraph 5.3 shall be followed except that the closures can be plastic or metal.
5.3 Process Seal “SS”: All process line open ends shall be sealed with a flange, a welded plate, a screwed plate, a brazed cap, a metallic spacer, or another pressure-sealing device as described in paragraphs 5.3.1 through 5.3.8. The sealed system shall be capable of maintaining a dry, oil‑free air pressure of 0.69 bar g (10 psig).
5.3.1 Watertight seals on the equipment that extends through the wall of the cold box, supplied by the equipment fabricator (plastic caps or other sealing devices), shall be removed and replaced with flanged, welded, screwed, or soldered closures.
5.3.2 All copper tube open ends shall be sealed with silver soldered fittings.
5.3.3 All threaded pipe open ends shall be sealed with threaded caps or plugs.
5.3.4 All other pipe open ends shall be sealed with welded plates, blind flanges, or by leaving the pressure test blanks in place.
5.3.5 All pipe open ends as a result of designated valves removed for shipping clearance purposes shall be sealed with a pipe cap or sheet metal.
5.3.6 The exterior flange of fully extractable valves shall be sealed using a 5 mm (3/16 inch) thick aluminum plate or the cover provided by the valve manufacturer and a 3 mm (1/8 inch) thick rubber gasket or the gasket provided by the valve supplier. Holes in the aluminum plate shall be drilled to match the valve’s bolt pattern.
5.3.7 When a butterfly valve is removed, the fabricator shall provide in its place a metallic spacer machined from the next larger size of pipe with the length that is equal to the valve’s face-to-face dimension. Gaskets and bolting shall be provided and installed to seal the opening and to maintain the shipping pressure.
5.3.8 The piping circuits shall be pressurized with dry, oil-free air (shall have a dewpoint of -40°C (-40°F) or lower and a hydrocarbon content of less than 5 mg per cubic meter) and all pipe open ends shall be sealed to retain this pressurized medium. A suitable, oil-free pressure gauge shall be installed in an accessible location for monitoring each circuit. Each circuit shall be pressurized to 0.5 ± 0.07 bar g (7 ±1 psig) with dry, oil-free air for shipment.
6. SEALING COLD BOX OPENINGS
6.1 All openings in the cold box shall be sealed in accordance with one of the methods described in Sections 6.2, 6.3, or 6.4 as specified in the project-specific documents.
6.2 Box Seal Type “O”: All openings in the jacket may be left open to the atmosphere. Drain holes shall be provided in each lower (shipping side) panel area of the cold box using a DN25 (NPS 1) pipe coupling so that all areas will drain any water. Pipe plugs shall be shipped loose. The box shall be inspected upon arrival at the site, and the piping and the equipment shall be washed down (if necessary) with clean, potable water. The cold box shall be completely drained, dried, and the pipe plugs installed before the addition of insulation. (This method is used when the shipping and erection times are of a short duration or when the cold box will be stored in a very dry climate.)
6.3 Box Seal Type “C”: All openings in the box structure shall be closed or covered with taped‑in‑place plastic or metal pipe caps (for valve openings and other penetrations), or sealed with metal or plywood panels. All tack welded and screwed panels shall have their edges sealed and waterproofed with tape. Other openings including thermocouple junction box openings shall be covered with shrink-wrap (plastic sheeting) that is taped in place using sealing tape. For sealing material requirements, see Section 10. Complete sealing of all openings shall provide a waterproof, watertight environment inside the box. As deemed necessary by the cold box fabricator, appropriate signs or warnings should be placed on sealed areas of the cold box where it is determined that it is unsafe for walking or working purposes.
6.3.1 All bolted removable access panels shall be gasketed with an adhesive, closed-cell PVC weather-strip foam tape, as specified in Air Products specification 4WCB-30001. Foam tape must be installed around all bolted access panels before the cold box leaves the fabrication shop.
6.3.2 Tack-welded panels shall be sealed with 75 mm (3 in) wide sealing tape (see Section 10 for material requirements) applied directly over the weld seam.
6.3.3 For openings greater than 75% of the box width, regardless of the opening length, it is recommended to span the full width of the box with steel sheet [minimum thickness 2 mm (0.06 in)], bending the sheet onto the adjacent box faces. The edges of the steel sheet shall be tack welded to the box, then sealed with tape (see paragraph 6.3.2). For openings less than 75% of the box width, regardless of the opening height, it is recommended to install raised curbing made of small structural angle or plate [minimum thickness 5 mm (0.2 in)] to create a dam to minimize water ingress. The steel sheet must be either stainless steel or carbon steel that is primed, to prevent rust streaks from forming during transport. In lieu of steel sheet, exterior grade plywood that is a minimum 12 mm (1/2 in) thick and securely fastened to temporary steel plates and/or angles using screws or bolts. All edges of plywood must be sealed with tape (see paragraph 6.3.2). For all said openings, the fabricator shall install temporary angle framing as required to adequately support the steel panels or plywood and maintain its integrity/shape during transport.
6.3.4 All other openings, including recessed thermocouple junction boxes, that could provide an entrance way for water shall be covered with shrink-wrap, (7 mil minimum, 10 mil maximum).The shrink-wrap shall be fully sealed to the cold box all around using pressure-sensitive sealing tape (see Section 10 for material requirements). Penetrations such as bolted and welded access panels, nozzles, instrument lines, or pressure taps need not be covered with shrink-wrap. The shrink-wrap may be tightened using a heat gun per the manufacturer’s instructions. The shrink-wrap shall be protected from puncture by sharp internal corners by taping foam rubber over any sharp objects.
6.3.5 Before applying any sealing tape as required in Section 6.3, all dust, welding soot, oil, and other contaminants shall be removed using a suitable degreasing solvent. The painted surfaces shall be allowed to adequately dry to prevent paint vapors from dissolving the tape adhesive.
6.3.6 Before sealing the last manway or large opening, the cold box shall be entered to check for light leaks that identify remaining unsealed openings, and to seal these openings in accordance with the requirements of this section. Also, the panel welds shall be checked for light leaks and shall be repaired accordingly. The light leak test shall be conducted during daylight or when the shop is well lit. In addition to the light leak test, the exterior of the box shall be inspected to ensure that all seal-welded panels are completely welded all around to provide a weather-tight seal.
6.4 Box Seal Type “CC”: This is a Type “C” Box Seal per Section 6.3 with the addition that the entire cold box structure be covered in shrink-wrap per Section 8 to provide an extra moisture-proof seal for shipment.
7. OPTIONS FOR SHIPPING SEALING METHODS
7.1 Possible options for the shipping sealing methods are contained in paragraphs 7.2, 7.3, and 7.4 as specified in the project-specific documents.
7.2 Shipping–Unsealed (S & O): This method requires that, as a minimum, Process Seal “S” and Box Seal “O” be used for box shipping sealing. This method is normally not preferred.
7.3 Shipping–Sealed (SS & C): This method requires that, as a minimum, Process Seal “SS” and Box Seal “C” be used for box shipping sealing. This method is used for boxes shipped with or without insulation over water and/or land.
7.4 Shipping–Extra Sealed (SS & CC): This method requires that, as a minimum, Process Seal “SS” and Box Seal “CC” be used for box preparation. This method may be used for sealing boxes shipped with or without insulation over water and/or land. This method will provide the greatest level of sealing.
8. COVERING COLD BOX WITH SHRINK-WRAP (PLASTIC SHEETING)
8.1 Shrink-wrap contractor to be selected by Cold Box Fabrication shop. Shrink-wrap and tape must satisfy the requirements in Section 10. Shrink-wrapping shall not cover D-rings and trunnions. Appropriate taping off around these items is required. Once the shrink-wrapping of the cold box is complete, Project will specify what visible information must be included on the shrink-wrap (that is, Project Name, Project Number, Destination, and so on). Center of gravity markings must be on the shrinkwrap. A minimum of (2) 75 mm (3 in) wide x 50 m (150 ft) long rolls of tape must be supplied to the land transportation crew before their departure from the shop. The additional tape is to be used by the Transporter to patch tears in the shrink-wrap resulting from the transit.
9. PROTECTIVE CAGES AND/OR SKIMMERS
9.1 If there are protrusions from the cold box that must be protected during shipping, the fabricator shall install temporary structural cages and/or skimmers from carbon steel angle and bars to protect them from damage caused by overhanging objects such as branches, wires, or other hanging items. Small stainless steel pads may be welded to the cold box panels to weld cage and/or skimmer steel to. The cages and/or skimmers can be cut off at the job site and the pad ground flush so that the painting system is not compromised or damaged. If cages protrude more than 75 mm (3 in) from the item being protected, the cold box fabricator shall notify Air Products Cold Box Engineering and Air Products Project Engineering for appropriate logistical planning.
10. MATERIAL RECOMMENDATIONS
10.1 The use of masking tape or duct tape is not permitted for sealing purposes. Only the herein specified sealing tape shall be used.
10.2 Degreasing solvent shall be suitable for use on painted metal.
10.3 For cold boxes fabricated in the US, use the materials listed in Table 1US:
Table 1US
| Materials | Description | Recommended Supplier |
| Sealing Tape | SCOTCH BRAND, No. 4811 manufactured by 3M Corp. (No Substitutions Allowed) Preservation Sealing Tape in 75 mm (3 inch) widths Acceptable Colors: White, Blue or Clear | XODE, Inc. 15519 Kutztown Road Kutztown, PA 19530-9303 Tel: (610) 683-8777 Tel: 1-800-772-9633 |
| Pipe Caps | Plastic | M & P Flange & Pipe Protection, Inc. 9426 Old Katy Rd. Houston, TX 77055 Tel: 1-800-888-2605 |
| Metal | M & P Flange & Pipe Protection, Inc. 9426 Old Katy Rd. Houston, TX 77055 Tel: 1-800-888-2605 | |
| Shrink-Wrap (Plastic Sheeting) | 7 mil (minimum) 10 mil (maximum) Acceptable Colors: White, Blue, or Clear | Shrinkit, Inc 812 Northwood Avenue Linden, NJ 07036 Tel: (908) 486-3533 Tel: 1-800-227-3998 or Mr. ShrinkWrap P.O. Box 697 Media, PA 19603 Tel: (610) 566-5290 Tel: 1-800-847-5290 |
| Sheet Metal | 2 mm thick (minimum) stainless steel or carbon steel with primer coating | N/A |
| Plywood | 12 mm thick (minimum) exterior grade | N/A |
10.4 For cold boxes fabricated in Asia, use the material listed in Table 1A:
Table 1A
| Materials | Description | Recommended Supplier |
| Sealing Tape | SCOTCH BRAND, No. 4811 manufactured by 3M Corp. (No Substitutions Allowed) Preservation Sealing Tape in 75 mm (3 inch) widths Acceptable Colors: White, Blue or Clear | XODE, Inc. 15519 Kutztown Road Kutztown, PA 19530 9303 Tel: (610) 683-8777 Tel: 1-800-772-9633 |
| Pipe Caps | Plastic | M & P Flange & Pipe Protection, Inc. 9426 Old Katy Rd. Houston, TX 77055 Tel: 1-800-888-2605 |
| Metal | M & P Flange & Pipe Protection, Inc. 9426 Old Katy Rd. Houston, TX 77055 Tel: 1-800-888-2605 | |
| Shrink-Wrap (Plastic Sheeting) | 7 mil (minimum) 10 mil (maximum) Acceptable Colors: White, Blue, or Clear | Shrinkit, Inc 812 Northwood Avenue Linden, NJ 07036 Tel: (908) 486-3533 Tel: 1-800-227-3998 or Mr. ShrinkWrap P.O. Box 697 Media, PA 19603 Tel: (610) 566-5290 Tel: 1-800-847-5290 |
| Sheet Metal | 2 mm thick (minimum) stainless steel or carbon steel with primer coating | N/A |
| Plywood | 12 mm thick (minimum) exterior grade | N/A |