Class 800LB Forged Carbon Steel Swing Check Valve (A105N) — 1", Metal Seat, Socket Weld (SW)

This Class 800LB forged carbon steel swing check valve is the 1" bolted bonnet design to BS 5352, with a swing disc and metallic seating surfaces. The body is forged ASTM A105N normalized carbon steel, with A105 available where normalization is not required and A350 LF2 available for low-temperature service. The seat and disc are F6a with an optional hardfaced (F6aHFS) sealing surface. Socket weld ends are to ASME B16.11; NPT, butt-weld and flanged ends are available on request. The valve is API 598 tested and is specified for small-bore high-pressure water, oil, gas and utility service lines.

Application

This 1" Class 800 forged carbon steel check valve is specified on small-bore high-pressure lines in oil and gas production and gathering, refinery and petrochemical process lines, power plant and utility systems, and general industrial service where a 1" socket-weld carbon steel check valve is required. The forged A105N body gives good strength and low-temperature toughness after normalization, the swing disc gives low pressure drop in the forward direction, and the socket weld ends give a permanent leak-tight joint for high-pressure small-bore pipe schedules. For low-temperature service, A350 LF2 is available; for sour service, NACE MR0175 compliance is available on request.

Standards

Design and manufacture: Forged steel check valve according to BS 5352.
Pressure-temperature ratings: ASME B16.34.
Socket weld end dimension: ASME B16.11.
Screw thread end (on request): ASME B1.20.1 (NPT).
Butt-weld end (on request): ASME B16.25.
Flanged end (on request): ASME B16.5.
Material: ASTM A105N / A105; A350 LF2 on request.
Inspection and test: API 598.
Sour service: NACE MR0175 / ISO 15156 on request.

Quick Details

1. Type: Forged carbon steel swing check valve
2. Design: Bolted bonnet, swing disc
3. Size: 1" (DN25); 1/2"–2 1/2" series available
4. Pressure Rating: ASME Class 800LB
5. End Connections: Socket weld (ASME B16.11); NPT (ASME B1.20.1), BW (ASME B16.25) and flanged (ASME B16.5) on request
6. Body Material: ASTM A105N (A105 optional); A350 LF2 on request
7. Various trim materials available to suit service conditions; F6aHFS hardfaced option
8. NACE MR0175 on request
9. Test and inspection: API 598

Selection Notes: A105N vs A105, Forged vs Cast at Class 800, and SW vs NPT

A105N vs A105: ASTM A105 is forged carbon steel in the as-forged or stress-relieved condition. ASTM A105N is the same chemistry but normalized after forging, which refines the grain structure and improves low-temperature toughness. A105N is preferred where the valve will see low ambient or low process temperatures, or where a normalized heat treatment is required by the line specification. This page is supplied in A105N as standard; A105 is available where normalization is not required, and A350 LF2 is available for low-temperature service below the A105N range.

Forged vs cast at 1" Class 800: at 1 inch and Class 800, the wall thickness and body shape are difficult to cast soundly, and forging gives a denser, more homogeneous section for high-pressure small-bore service. BS 5352 is the design standard for forged steel check valves, while BS 1868 covers cast steel check valves. The forged body also machines more predictably for the socket weld end preparation.

SW vs NPT ends: socket weld ends to ASME B16.11 give a permanent, leak-tight joint and are preferred for high-pressure, high-temperature, sour or toxic service where a threaded joint could loosen or leak. NPT threaded ends to ASME B1.20.1 allow faster assembly and disassembly and are common on utility, instrument and small-bore process lines. This page is the SW version; NPT, BW and flanged ends are available on request. For NACE MR0175 sour service, SW ends are more frequently specified because the threaded joint is an additional leak path.

Features

1. General
Bolted bonnet;
Swing disc;
Metallic seating surfaces.

2. Pressure-Temperature Ratings
Ratings to ASME B16.34; Class 800 at 100°F (38°C) is 1975 psi (13.8 MPa) for ASTM A105N carbon steel. A105N is normalized after forging for improved low-temperature toughness. Refer to ASME B16.34 for the derating curve at elevated temperature.

3. Body and Bonnet Connection
Class 800LB forged check valves are supplied with a bolted bonnet as standard; welded bonnet is available on request.

4. Cover Gasket Style
Stainless steel + flexible graphite wound gasket is used for Class 800LB check valve;
Metal gasket and metal ring gasket are also optional.

5. Seat
For carbon steel check valve, the seat is usually forged steel. The seat sealing surface may be spray-welded with hard alloy (F6aHFS) if specified by the customer.

Forged Carbon Steel Swing Check Valve Parts and Material List (Class 800LB)

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Parts numbers follow the original drawing; numbers not listed are lift-type or ball-type parts and do not apply to this swing-type valve. Part 33 "Steel ball" in the original source is a ball check valve part and has been removed. Gasket corrected from "304+ Flexible garphite" to "304 + Flexible graphite". Disc Nut corrected from "8" to "ASTM A194 8". Body and Bonnet are listed as A105N on this page, since A105N is the standard supply for this specification; A105 is available where normalization is not required.

Main Connection Dimensions — Class 800LB Reduced Port Swing Type (mm)

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Dimensions in mm. L = face-to-face for SW ends; H = centreline to top of bonnet; d = flow port diameter (reduced port). The 1" row (NPS 1, L = 111 mm, H = 78 mm, d = 18 mm, 3.3 kg) is the specification of this page; the remaining rows are the 1/2"–2 1/2" Class 800 reduced-port swing series for reference. The original source table mixed lift-type and full-port (FP) data in the same rows; this table has been filtered to the reduced-port (RP) swing-type series only. In the original data the flow-port values "105" and "135" and the weight values "14", "15" and "17" had lost their decimal points; they are corrected here to 10.5, 13.5, 1.4, 1.5 and 1.7 respectively. Full-port and lift-type dimensions are available on request.

Frequently Asked Questions