Rating of Cast Iron Pipe Fittings

**Rating of Cast Iron Pipe Fittings (Threaded Fittings, ANSI B16.4)**
Temperature, °F	Working pressures, nonshock, psig (Class 125)	Working pressures, nonshock, psig (Class 250)
-20 to 150	175	400
200	165	370
250	150	340
300	140	310
350	125	280
400	NA	250

**Rating of Cast Iron Pipe Fittings (Flanged Fittings, ANSI B16.1)**
Temperature, °F	Class 125 (1–12 in)	Class 125 (14–24 in)	Class 125 (30–48 in)	Class 250 (1–12 in)	Class 250 (14–24 in)*
-20 to 150	200	150	150	500	300
200	190	135	115	460	280
225	180	130	100	440	270
250	175	125	85	415	260
275	170	120	65	395	250
300	165	110	50	375	240
325	155	105	NA	355	230
350†	150	100	NA	335	220
375‡	145	NA	NA	315	210
400§	140	NA	NA	290	200
425	130	NA	NA	270	NA
450	125	NA	NA	250	NA

NOTES: NA = not acceptable. *For liquid service, these ratings are for class 250 flanges only, not for class 250 fittings. †353°F to reflect 125-psig steam pressure. ‡406°F to reflect 250-psig steam pressure.

SOURCE: Data adapted from ANSI B16.4 and ANSI B16.1 standards for cast iron pipe fittings.