API 594 Class 900LB Swing Check Valve (H44H) — A216 WCB, Bolted Cover, RJ Flanged Ends

This Class 900LB swing check valve is the API 594 / BS 1868 cast steel design with a bolted cover (B.C), swing disc and metal seat hardfaced (HF). The body is ASTM A216 WCB, with the seat and disc sealing surfaces hardfaced as Trim 1 (13Cr), Trim 5 (STL) or Trim 8 (13Cr + STL). Flanged ends are RJ (ring joint / RTJ) to ASME B16.5 as standard at Class 900; RF is also available for non-sour service. Sizes run from NPS 2" to NPS 24". The cover gasket is a metal ring gasket, and the cover is removable for disc and seat inspection without removing the valve from the line.

Application

This API 594 Class 900 swing check valve is specified in high-pressure oil and gas, petrochemical and refinery process lines, power generation and high-energy utility service where reverse-flow protection is required at Class 900. The swing disc provides low pressure drop and full-bore flow, the bolted cover allows inline inspection of the disc and seat, and the RJ flanged ends provide a metal-to-metal seal at high pressure. For sour service the valve can be supplied to NACE MR0175 / ISO 15156 on request.

Standards

Design and manufacture: Cast steel check valve according to BS 1868, API 594, ASME B16.34 and API 6D; forged steel check valve according to API 602.
Inspection and test: API 598 or API 6D.
End flange dimension: ASME B16.5 (for NPS ≤ 24); ASME B16.47 series B, API 605 or ASME B16.47 series A / MSS SP-44 (for NPS > 24).
BW end dimension: ASME B16.25.
Face to face and end to end: ASME B16.10.
Pressure-temperature ratings: ASME B16.34.
Shell wall thickness: API 600 and BS 1868.

Quick Details

1. Type: WCB swing check valve
2. Bonnet type: Bolted cover (B.C)
3. Disc type: Swing disc
4. Size Range: 2" to 24" (DN50 to DN600)
5. Pressure Rating: ASME Class 900LB / 900#
6. End Connections: Flanged — RJ (RTJ) standard, RF available
7. Materials: Cast steel in WCB, LCB, CF8, CF8M, CF3, CF3M, WC6, WC9, C5, C12, 4A, 5A or equivalent
8. Various trim materials available to suit service conditions
9. NACE MR0175 on request

Selection Notes: API 594, Bolted Cover (B.C) and RJ Ends

API 594 vs API 6D / BS 1868: API 594 covers flanged and wafer-type check valves, and specifies face-to-face dimensions, pressure-temperature ratings and test requirements specific to the check valve product. API 6D covers pipeline valves generally, and BS 1868 is the equivalent British standard for flanged and butt-weld check valves. The same valve can be supplied to any of these standards; the required standard should be stated on the inquiry. API 594 is commonly specified for refinery, petrochemical and general plant piping, and API 6D remains the standard for pipeline service.

Bolted cover (B.C): on a bolted cover swing check valve, the cover is held to the body by studs and nuts, with a gasket sealing the joint. The cover can be removed to inspect or replace the disc, arm and seat without removing the valve from the line. At Class 900, a bolted cover with a metal ring gasket is the standard construction; a pressure seal bonnet is normally used only at Class 1500 and above. This page covers the bolted cover (B.C) configuration.

RJ (ring joint) ends: RJ (also written RTJ) flanged ends use a metal ring gasket seated in a machined groove on the flange face, providing a metal-to-metal seal. At Class 900, RJ ends are the standard choice for high-pressure, high-temperature and sour service, and are frequently specified together with NACE MR0175. RF (raised face) ends are also available on this valve for non-sour service, but RJ is the more common selection at Class 900. The face-to-face dimensions differ slightly between RF and RJ, and both are listed in the dimension table on this page.

Features

1. General
Bolted cover (B.C) / pressure sealing bonnet;
Swing disc;
Metallic seating surfaces.

2. Body and Bonnet Connection
Class 900LB check valves are normally supplied with a bolted cover.

3. Cover Gasket Style
Metal ring gasket;
Pressure seal cover / bonnet design available for higher pressure classes.

4. Seat
For carbon steel check valve, the seat is usually forged steel. The seat sealing surface may be spray-welded with hard alloy if specified by the customer. For stainless steel check valve, an integral seat is usually adopted, or it can be machined integrally after hard alloy welding. Threaded or welded type seat is also optional for stainless steel check valve if requested by the customer.

Swing Check Valve Parts and Material List (Class 900LB)

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Parts No. 1 Body: original source had "ASTM A216WCB" — corrected to "ASTM A216 WCB". Parts No. 3 Disc: original source had "ASTMA216WCB+13Cr" — corrected to "ASTM A216 WCB + 13Cr". Parts No. 8 Bonnet Nut (CF8 column): original source had "ASTM A1948" — corrected to "ASTM A194 8". Parts No. 9: original source had "Bon net bolt" — corrected to "Bonnet Bolt". Eye Bolt is listed as ASTM A181 in all five columns as in the original; confirm against the material certificate — eyebolts are often supplied in A36 or A193 B7.

Main Connection Dimensions — Class 900LB (mm)

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Dimensions in mm. L = face-to-face dimension (RF / RTJ) or end-to-end (BW) per ASME B16.10. RF and RTJ flange dimensions per ASME B16.5 for NPS ≤ 24. This page covers the RJ flanged configuration; the RF and BW columns are listed for reference. The original source dimension table was titled "Class 1500LB" but the table header reads "900Lb" — this page follows the 900LB content, matching the product title and Quick Details.

Frequently Asked Questions