Size and class
DN 50, NPS 2 and the Japanese 50A or 2B are one nominal size. PN 16, ASME Class 150 and JIS 10K are pressure classes of three systems; their flanges differ in most sizes.
Reference tool — not inspection
Read the valve body before it goes in an RFQ.
Valve body marking
Size, class, material, arrow.
Type the marks as they are cast, then choose the valve type and its ends. Below the examples, an offered replacement’s marking can be checked against it: size, rating and material. The drawing and the RFQ line update with every change.
Separate the marks with spaces.
Examples:
Replacement check
On the markings alone: the valve’s data sheet, its end dimensions and the service decide.
All 130 engineering tools
A valve body carries its identity in the casting: the nominal size, the pressure class, the body material and, on one-way valves, a flow arrow. EN 19 and MSS SP-25 set out what is marked; the maker’s mark and a heat number usually sit beside them. Type what is cast on the body, and the reader explains each mark and writes the RFQ line.
Pressure classes are designations, not working pressures: what a valve may carry at a temperature depends on its body material. Comparable grades from other standards are close, not identical — the material certificate decides.
How a valve body is read
Size, material, arrow.
Material code
GG-25 and EN-GJL-250 are one grey iron; GGG-40 is the ductile EN-GJS-400-15. WCB, CF8M and SCS14A are cast steels; CAC406, B62 and CC491K are gunmetals of one type.
Arrow and other marks
An arrow means the valve works one way only. Other numbers — a heat number, a figure number — identify the casting or the model: quote them as cast.
| As marked | Standard | What it is | Comparable |
|---|---|---|---|
| EN-GJL-250 (GG-25) | EN 1561 | grey cast iron, at least 250 MPa | JIS FC250 |
| EN-GJS-400-15 (GGG-40) | EN 1563 | ductile iron, 400 MPa, 15 % elongation | — |
| EN-GJS-400-18-LT (GGG-40.3) | EN 1563 | ductile iron, impact-tested at low temperature | — |
| EN-GJS-500-7 (GGG-50) | EN 1563 | ductile iron, 500 MPa, 7 % elongation | — |
| 1.0619 GP240GH (GS-C25) | EN 10213 | cast carbon steel for pressure purposes | ASTM A216 WCB |
| 1.4308 | EN 10213 | cast stainless steel, 304 type | ASTM A351 CF8, JIS SCS13A |
| 1.4408 | EN 10213 | cast stainless steel, 316 type | ASTM A351 CF8M, JIS SCS14A |
| WCB, WCC | ASTM A216 | carbon steel castings for high-temperature service | 1.0619 (WCB) |
| LCB, LCC | ASTM A352 | steel castings for low-temperature service | — |
| WC6, WC9 | ASTM A217 | alloy steel castings for high-temperature service | — |
| A105 | ASTM A105 | carbon steel forgings for piping components | — |
| F316 | ASTM A182 | forged stainless steel, type 316 | — |
| FC200, FC250 | JIS G 5501 | grey cast iron, the number is MPa | EN-GJL-200, EN-GJL-250 |
| FCD450 | JIS G 5502 | ductile iron, at least 450 MPa | EN-GJS-450-10 |
| SCPH2 | JIS G 5151 | cast steel for pressure parts at high temperature | — |
| SCS13A, SCS14A | JIS G 5121 | cast stainless steel, 304 and 316 type | CF8, CF8M |
| CAC406 (BC6) | JIS H 5120 | leaded gunmetal, 85-5-5-5 type | C83600, CC491K, LG2 |
| B62 C83600 | ASTM B62 | composition bronze, 85-5-5-5 | CC491K, CAC406 |
| C95800 | ASTM B148 | nickel aluminium bronze, for sea water | CC333G |
| CW617N | EN 12165 | forged brass, not dezincification-resistant | — |
Comparable grades are close in composition and purpose, not identical: the material certificate decides. Where two tables disagree, no comparison is given.
Sources
What a valve body carries: EN 19 (nominal size, PN or Class, material, maker, flow arrow) per the standard’s published contents, and MSS SP-25 and ASME B16.34 (maker, rating, material with its heat number, size) per Wermac’s marking summary. JIS classes: Samson’s technical documentation (10K, a flange designed for 10 kgf/cm²). WOG and SWP: QRFS and Milwaukee Valve data sheets. PS and TS: the Pressure Equipment Directive 2014/68/EU. Comparable grades only where two tables agree: VAG’s material tables, Sulzer’s cast materials, azbil’s valve data (SCS13A with CF8, SCS14A with CF8M), an ASTM and JIS comparison chart, NBK’s comparison table, Kipp and Applus data sheets for the EN cast irons, Metoree and Righton Blackburns for CAC406, C83600, CC491K and LG2, Zollern for C95800 and CC333G. ASTM scopes per the ASTM catalogue titles.
Before you send the marking
Questions about valve markings in an RFQ
What does PN 16 on a valve body mean?
PN 16 is the EN pressure designation of the valve (EN 1333): a rounded reference number, not the working pressure. What the valve may carry at a given temperature comes from the pressure-temperature table for its body material, and its flanges follow EN 1092. Give the PN together with the medium and the temperature.
Is ASME Class 150 the same as 150 psi?
No. Class 150 is a pressure class of ASME B16.34 for valves and B16.5 for flanges, not a pressure in psi: the allowable pressure depends on the material group and the temperature. Marks such as 200 WOG on bronze valves are makers’ ratings in psi, not ASME classes.
What do 5K and 10K mean on a Japanese valve?
They are JIS pressure classes: 10K was originally a design pressure of 10 kgf/cm². Japanese valves give the size in A (millimetres, like DN) or B (inches), so 50A and 2B are one size. JIS flanges differ from PN 16 and Class 150 flanges in most sizes: check the bolt circle with the flange identifier.
What do WOG and SWP mean?
WOG (water, oil, gas), also marked CWP, is the cold working pressure in psi at ambient temperature; SWP or WSP is the rating on saturated steam, which is lower. Both are makers’ ratings, common on bronze and small threaded valves: 200 WOG is about 13.8 bar.
Is GG-25 the same as EN-GJL-250?
Yes: GG-25 is the old DIN name of the same grey iron, and GGG-40 the old name of the ductile iron EN-GJS-400-15. Grades from other standards, such as SCS14A, CF8M and 1.4408, or CAC406, C83600 and CC491K, are comparable, not identical: the material certificate decides.
What else should the request include?
The maker and the figure number from the nameplate or the handwheel tag, the valve type and how it is operated, the ends, the face-to-face length measured flange face to flange face, the medium and its temperature, and photographs of both sides of the body. EN 558 and ASME B16.10 standardise face-to-face lengths by series, so the length helps to tell the right replacement.
Body read?
Send the line with the photographs.
A decoded marking is a cross-check, not proof. Attach photographs of both sides of the body and the nameplate, give the medium and the temperature, and Vessel Core checks them against each other before an offer goes back.
Buyer tools
