ASME B16.9 buttweld fittings dimensions

Centre-to-end and overall dimensions (mm) of ASME B16.9 factory-made wrought buttweld fittings: long-radius and short-radius elbows, equal tees, concentric and eccentric reducers and caps.

NPS	90° LR elbow A	45° LR elbow B	90° SR elbow A	Equal tee C	Reducer length H	Cap E
1/2"	38	16	–	25	–	25
3/4"	29	11	–	29	38	25
1"	38	22	25	38	51	38
1-1/4"	48	25	32	48	51	38
1-1/2"	57	29	38	57	64	38
2"	76	35	51	64	76	38
2-1/2"	95	44	64	76	89	38
3"	114	51	76	86	89	51
3-1/2"	133	57	89	95	102	64
4"	152	64	102	105	102	64
5"	190	79	127	124	127	76
6"	229	95	152	143	140	89
8"	305	127	203	178	152	102
10"	381	159	254	216	178	127
12"	457	190	305	254	203	152
14"	533	222	356	279	330	165
16"	610	254	406	305	356	178
18"	686	286	457	343	381	203
20"	762	318	508	381	508	229
24"	914	381	610	432	508	267

Long-radius elbow radius = 1.5 × NPS; short-radius = 1.0 × NPS. Cap length shown is for standard wall; heavier walls may be longer.

Choosing LR or SR elbows

Long-radius elbows are the default in process piping because they give lower pressure drop and smoother flow. Short-radius elbows save space but carry a reduced pressure rating in ASME B31.3 calculations. Reducer lengths (H) are the same for concentric and eccentric reducers of the same size.

Frequently asked questions

What is the centre-to-end of a 6 inch LR 90° elbow?

229 mm (9 inches), i.e. 1.5 × the nominal size.

What is the difference between LR and SR elbows?

LR elbows have a bend radius of 1.5 × NPS and SR elbows 1.0 × NPS. SR elbows are more compact but cause more pressure drop.

Which standard covers buttweld fittings?

ASME B16.9 covers factory-made wrought buttweld fittings NPS ½ to 48. MSS SP-75 covers high-yield fittings.

Last updated 2026-11-02