KEY FEATURES

• Standard: GB/T 44916-2024 / ISO 19037:2019

• Application: Ultra-low temperature (-196°C to -50°C)

• Structure Type: Outside Screw and Yoke (OS&Y), Bolted Bonnet, Rising Stem

• Extended Bonnet: Mandatory for cryogenic service to keep packing away from the cold zone.

• Design Temperature Range: -196°C to +100°C

• Inspection Standard: ISO 5208, API 598

• Safety Feature: Pressure relief hole to prevent abnormal pressure rise in the body cavity.

1. MEDIA TYPES AND PRESSURE-TEMPERATURE RATINGS

TABLE 1 - MEDIA TYPES

TABLE 2 - WORKING PRESSURE AND DESIGN TEMPERATURE

Note: Pressure ratings correspond to ASME B16.34. Design temperature shall be between -196°C and 100°C. When the pressure class exceeds Class900, it may be agreed upon by both parties. Working pressure depends on the purchaser's piping system.

2. MATERIALS OF MAIN PARTS

TABLE 3 - MATERIALS FOR MANUFACTURING METHODS

Note: Other materials may be used provided they are equivalent to or better than the specified materials in terms of manufacturing process, mechanical properties, and corrosion resistance. Materials shall also comply with the working temperature and mechanical properties, including low-temperature impact toughness and corrosion resistance.

3. DESIGN AND CONSTRUCTION

3.1 BASIC STRUCTURE
The gate valve shall be of the Outside Screw and Yoke (OS&Y) type, bolted bonnet, rising stem, and shall have an extended bonnet. The valve shall be designed with a pressure relief hole to prevent abnormal pressure rise in the body cavity. The structure and function shall comply with the specified requirements.

3.2 BODY

• Type: Full bore (straight-through).

• Structural Length: Shall comply with ASME B16.10.

• Wall Thickness: Shall comply with ASME B16.34.

• End Connections:

• Butt-welding ends: Shall comply with ASME B16.25.

• Flanged ends: NPS24 (DN600) and below shall comply with ASME B16.5. Class150 and Class300 shall use raised face (RF) flanges; Class600 and above shall use large tongue (LGF) flanges or raised face (RF) flanges, complying with ASME B16.5 and ASME B16.47.

• Surface Finish: Raised face (RF) flanges shall have a surface roughness of Ra 3.2 μm to Ra 6.3 μm (125 μm to 250 μm). Large tongue (LGF) flanges shall have a surface roughness of less than Ra 3.2 μm (125 μm).

3.3 EXTENDED BONNET

• Design: The extension length shall ensure the packing is away from the cryogenic zone. The extension length must comply with ISO 28921-1. Vent holes shall be designed to prevent ice blockage. An isolation sleeve and drip plate may be installed on the extension.

• Material:

• Castings: ASTM A351 CF3, CF3M.

• Forgings: ASTM A182 F304L, F316L.

• Pipe/Connections: ASTM A312 or equivalent A358 304L/316L. Seamless pipes or longitudinally welded pipes are required. Spiral welded pipes are not allowed.

3.4 GATE (DISC)

• Design: The gate shall be a single-piece, solid type. It shall be guided to minimize wear during operation. The guide shall be aligned with the valve seat. The disc shall not deform under working pressure, and the connection with the stem shall be T-slot or spherical. Threads shall comply with ASME B1.5 or B1.8.

• Material: ASTM A182 F316, ASTM A351 CF8M, or better. The sealing surface shall be surface-hardened with a minimum thickness of 1.6 mm.

3.5 STEM

• Design: The stem shall be of the rising type. The minimum diameter shall comply with BS 1873. The stem surface in contact with packing must be precision-finished to 0.8 μm to prevent leakage.

• Material: ASTM A182 F316 or better.

3.6 STEM SEALING (PACKING)

• The stem shall be sealed with a suitable structure (e.g., packing box, sealing ring) to prevent leakage.

• Packing materials shall be graphite, PTFE, or braided PTFE. The packing shall not chemically react with the process fluid.

• The packing must be replaceable without removing the valve from the line.

3.7 PRESSURE RELIEF

• The gate must have a pressure relief hole to prevent abnormal pressure rise in the body cavity. For double-disc gates, an internal system must be installed to eliminate abnormal pressure rise. The size of the pressure relief hole shall comply with ASME B16.34.

4. INSPECTION AND TESTING

4.1 MATERIAL INSPECTION

• Chemical composition, mechanical properties, and low-temperature impact tests shall be conducted on main parts.

• Impact Test: At -196°C, the minimum lateral expansion of 3 specimens shall be greater than 0.381 mm. The ferrite content in austenitic stainless steel shall be between 5% and 10%.

4.2 NON-DESTRUCTIVE TESTING (NDT)

• Radiographic Testing (RT): Weld seams shall be 100% RT. Acceptance criteria per ASME B16.34 and MSS SP-55.

• Penetrant Testing (PT): Per ASME BPVC Sec. V Art. 6.

• Ultrasonic Testing (UT): Per ASME BPVC Sec. V Art. 4.

4.3 WELDING AND HEAT TREATMENT

• Welding shall be performed according to qualified WPS/PQR. NDT of welds shall be agreed upon by both parties.

• Heat treatment shall be agreed upon by both parties.

4.4 SURFACE TREATMENT

• All surfaces of the valve shall be pickled and passivated.

5. INQUIRY REQUIREMENTS (FOR BUYERS)

To ensure an accurate quotation and compliance with GB/T 44916-2024 / ISO 19037:2019, please provide the following details:

• Product Name: Marine Cryogenic Gate Valve

• Standard: GB/T 44916-2024 / ISO 19037:2019

• Nominal Diameter (DN/NPS): [e.g., 25, 50, 100]

• Nominal Pressure (Class): [e.g., Class150, Class300, Class600]

• Working Medium: [e.g., LNG, NG, LN2, N2]

• Design Temperature: [e.g., -196°C]

• End Connection: [ ] Flanged (RF/LGF) / [ ] Butt-welding

• Body Material & Manufacturing Method: [ ] Forged (ASTM A182 F304/F316/L) / [ ] Cast (ASTM A351 CF8/CF8M/CF3/CF3M)

• Operation Type: [ ] Handwheel / [ ] Gearbox

• Classification Society Required: [e.g., NK, LR, DNV, ABS, CCS, or None]

• Quantity: [e.g., 10 pcs]

• Destination Port: [e.g., Singapore, Rotterdam]

• Inspection Requirements: [e.g., EN 10204 3.1 Certificate, Third-Party Witness]