Carbon Steel Socket Weld Fittings Manufacturer

Solitaire Overseas supplies carbon steel socket weld fittings forged in ASTM A105 and machined to ASME B16.11 dimensions for fillet welded, small bore piping. Unlike a threaded joint, a socket weld connection is fully welded around the fitting bore, giving a more permanent, leak resistant seal for high pressure and vibration prone service. Available in Class 3000, 6000 and 9000 across NPS 1/8 inch to 4 inch, our socket weld range covers elbows, tees, crosses, couplings and unions, each supplied with complete mill test certification and dimensional inspection.

Not sure whether socket weld or threaded fittings suit your piping class?

Contact Solitaire Overseas for a quote, or compare all carbon steel fitting types on our Carbon Steel Pipe Fittings hub page.

Chemical Composition, Mechanical Properties and Pressure Class Reference

Specifications Chemical Composition Mechanical Properties Equivalents Pressure Rating Dimensions

Carbon Steel Socket Weld Fittings Specifications

Parameter	Specification
Standard	ASTM A105, ASME B16.11
Size Range	NPS 1/8" to 4"
Pressure Class	3000#, 6000#, 9000#
End Type	Socket weld (fillet weld into socket bore)
Manufacturing	Forged from solid bar/billet, machined to size
Socket Depth / Concentricity	Per ASME B16.11 Table 1, concentricity within 0.03 in (0.8 mm)
Hardness	137 to 197 HB
Certification	Mill Test Certificate EN 10204 3.1, 3.2 on request

Chemical Composition (A105, %)

C max	Mn	P max	S max	Si
0.35	0.60 – 1.05	0.035	0.040	0.10 – 0.35

Mechanical Properties (A105)

Tensile Strength min	Yield Strength min	Elongation min	Hardness
485 MPa (70 ksi)	250 MPa (36 ksi)	22%	137 – 197 HB

Approximate International Equivalents

ASTM	EN	JIS
A105	P245GH / P250GH (1.0460), EN 10222-2	G3201 SF440A / SF490A

Carbon Steel Socket Welding Fittings Pressure Rating

Class 3000	100°F	200°F	300°F
	2570	2280	2055
400°F	500°F	700°F
1870	1715	1480
800°F	900°F	1000°F
1370	1290	1250

Carbon Steel Socket Weld Fittings Dimensions

NOM BORE	PIPE O.D.	Class 3000 A max.	Class 3000 B max.	COMMON FACTORS K	COMMON FACTORS J	COMMON FACTORS L	COMMON FACTORS M	COMMON FACTORS N	COMMON FACTORS P	COMMON FACTORS Q	COMMON FACTORS C min.	COMMON FACTORS D min.	COMMON FACTORS O min.	COMMON FACTORS O max.	Class 6000 A	Class 6000 B	Class 6000 M	Class 6000 K	Class 6000 N
1/8"	10.3	22	18.5	26	16	40	17.3	32	15	10	10.7	10	5	8	22	22	20	25	46
1/4"	13.7	22	22	26	18	43	21.2	32	15	10	14.1	10	5	8	27	25	24	25	51
3/8"	17.2	25	25	26	19	48	25.4	36	16.5	10	17.6	10	3	9	27	28	28	26	60
1/2"	21.3	27	32	30	21	51	31	41	16.5	10	21.7	10	6	13	31	34	34	31	72
3/4"	26.7	34	38	36	24	57	37	50	19.5	13	27	13	6	13	37	42	41	35	80
1"	33.4	37	46	40	25	64	45.2	60	22.5	13	33.8	13	9	17	42	50	50	40	94
1 1/4"	42.2	42	56	40	29	70	55	70	22.5	13	42.6	13	9	17	47	59	58	41	100
1 1/2"	48.3	47	62	40	30	79	61.4	78	24	13	48.7	13	9	17	53	67	66	43	122
2"	60.3	56	75	52	37	89	75	95	29	13	61.2	16	15	23	59	84	83	55
2 1/2"	73.02	60	92	52	48	114	91.3	125	32	16	73.8	16	14	24		102		56
3"	89.00	76	110	52	51	127	108.8	140	35	16	89.8	16	14	24		121		58
4"	114.50	88	137	58		150	136.9		42	19	115.5	19	14	24		152		64

Types of Carbon Steel Socket Weld Fittings

Tee Socket Weld

Socket Weld Union

Socket Weld 90a Branch Outlet

Socket Weld 90° Elbow Outlet

Socket Weld 45° Branch Outlet

Reducing Coupling Socket Weld

Reducer Insert Socket Weld

Nipple Branch outlet butt weld

Half-Coupling-Socket-Weld

Full Coupling Socket Weld

Eccentric Reducer Coupling Socket Weld

Cross Socket Weld

Couplet Socket Weld

Cap Socket Weld

Butt Weld 90a Elbow Outlet

Butt Weld 90 Branch Outlet

Butt Weld 45° Branch Outlet

Boss Socket Weld

90° Elbow Socket Weld

45º Lateral Tee Socket Weld

45° Elbow Socket Weld

Applications of Carbon Steel Socket Weld Fittings

Instrumentation lines
Hydraulic and pneumatic piping
Small bore high pressure process connections
Skid mounted and package unit piping
Steam and condensate lines in small bore

Socket Weld vs Threaded vs Butt Weld Fittings

Socket weld is one of three common end connections for carbon steel pipe fittings. Here is how the three compare.

Feature	Socket Weld	Threaded	Butt Weld
Typical Size Range	NPS 1/8" to 4"	NPS 1/8" to 4"	NPS 1/2" to 48"
Joint Type	Fillet weld into socket	Mechanical thread (NPT/BSPT)	Full penetration weld
Pressure Capability	Up to Class 9000	Up to Class 6000	High, size dependent
Dismantling	Must be cut out	Unscrews for maintenance	Must be cut out
Best Suited For	Permanent small bore, high pressure or vibration prone joints	Small bore, frequently serviced joints	Large bore continuous pipelines
Learn More	This page	Carbon Steel Threaded Fittings	Carbon Steel Buttweld Fittings

Frequently Asked Questions

What sizes are available in carbon steel socket weld fittings?

NPS 1/8 inch through 4 inch, per ASME B16.11.

What is the difference between socket weld and threaded fittings?

Socket weld fittings are joined by fillet welding around the socket, giving a more leak tight, permanent joint than a threaded connection, which relies on a mechanical thread seal.

Can socket weld fittings be used interchangeably with threaded fittings?

No. Socket weld fittings require a plain pipe end that slides into a machined socket for fillet welding, while threaded fittings need a pipe end cut with matching NPT or BSPT threads; the two end preparations are not interchangeable on the same pipe end.

Is a gap required inside the socket weld joint?

Yes, ASME B16.11 and B31.3 call for a small gap, typically about 1.6 mm (1/16 inch), between the pipe end and the base of the socket before welding, to allow for thermal expansion and avoid stress at the weld root.

What is the minimum order quantity for socket weld fittings?

MOQs vary by size and class; share your bill of materials with our sales team for a size wise quotation and lead time.

Do you provide PMI or radiography testing on socket weld fittings?

Yes, positive material identification and other supplementary testing can be arranged on request in addition to the standard mill test certificate.