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Alloy Steel Weldolet

Views: 1 Author: Site Editor Publish Time: 2025-07-09 Origin: Site

Alloy steel weldolet is a kind of key pipe fittings used for connecting branch pipe and main pipe in pipeline system, the main function is to connect the branch pipe firmly by welding after opening holes on the main pipe, meanwhile ensure the sealing, pressure resistance and structural strength of pipeline system. The material is made of alloy steel (such as chrome molybdenum steel, nickel-based alloy, etc.), which is suitable for high temperature, high pressure, corrosive and other complex working conditions, widely used in petrochemical, electric power, coal chemical, natural gas and other industrial fields.

Specification of MSS SP-97 Weldolet Fittings

Size Range	1/8" - 24" / DN6 - DN600
Schedule Chart	STD, XS, SCH 160
Standard	MSS SP-97
Alloy Steel	ASTM A182 F11 / 12 / 22 / 5 / 9 / 91 / 92 / 22

Alloy Steel Weldolet Manufacturing Standards:

ASTM A182

Standard Specification for Wrought Austenitic Steel Piping Fittings

ASME B16.11

This is the American Standard for forged socket weld, threaded and butt weld fittings, to which alloy butt weld standoffs are often referred for design and manufacture.

MSS SP-97

Standard for integrally reinforced forged branch sockets for socket welding, threaded, and butt welding.

Characteristics of Alloy Steel Weldolet

High temperature resistance performance: Alloy steel weldolet usually contain chromium, molybdenum, nickel and other alloying elements, which enables them to maintain high strength, hardness and creep resistance in high temperature environment, suitable for high temperature and high pressure fluid transportation.

Corrosion resistance: according to the different alloy composition, alloy steel can effectively resist the erosion of acid, alkali, salt and other corrosive media, especially in the chemical industry, petrochemical and other industries with high requirements for corrosion resistance.

High strength and toughness: Alloy steel weldolet has higher tensile strength and yield strength, as well as good impact toughness, can withstand greater pressure and external loads.

Pressure resistance and fatigue resistance: the need to withstand the system working pressure and temperature fluctuations brought about by the alternating stress, so the butt-welded parts need to ensure that there are no welding defects through non-destructive testing to avoid cracking and leakage.

Structural strength and stress dispersion: after the main opening will produce stress concentration, the curved fit design of the weldolet needs to be consistent with the curvature of the main pipe, and after welding to reduce the residual stress through heat treatment, to avoid fracture of the fittings due to stress concentration in the long-term use of the fittings.

ASTM A182 Weldolet Chemical Composition

CHEMICAL	LIMITS	C	Mn	P	S	Si	Ni	Cr	Mo	Cb
ASTM A182 F11 CL1	MIN	0.05	0.30			0.50		1.00	0.44
ASTM A182 F11 CL1	MAX	0.15	0.60	0.03	0.03	1.00		1.50	0.65
ASTM A182 F11 CL2	MIN	0.10	0.30			0.50		1.00	0.44
ASTM A182 F11 CL2	MAX	0.20	0.80	0.04	0.04	1.00		1.50	0.65
ASTM A182 F11 CL3	MIN	0.05	0.30			0.50		1.00	0.44
ASTM A182 F11 CL3	MAX	0.15	0.60	0.03	0.03	1.00		1.50	0.65
ASTM A182 F12 CL1	MIN	0.05	0.30					0.80	0.44
ASTM A182 F12 CL1	MAX	0.15	0.60	0.45	0.45	0.50		1.25	0.65
ASTM A182 F12 CL2	MIN	0.10	0.30			0.10		0.80	0.44
ASTM A182 F12 CL2	MAX	0.20	0.80	0.40	0.40	0.60		1.25	0.65
ASTM A182 F22 CL1，CL3	MIN	0.05	0.30					2.00	0.87
ASTM A182 F22 CL1，CL3	MAX	0.15	0.60	0.04	0.04	0.50		2.50	1.13
ASTM A182 F91	MIN	0.08	0.30			0.02		8.00	0.85	0.06
ASTM A182 F91	MAX	0.12	0.60	0.02	0.01	0.50	0.40	9.50	1.05	0.10
ASTM A182 F92	MIN	0.07	0.30					8.50	0.30	0.04
ASTM A182 F92	MAX	0.13	0.60	0.02	0.01	0.50	0.40	9.50	0.60	0.09

ASTM A182 Weldolet Mechanical Property

MATERIAL	ASTM A182 F11 CL1	ASTM A182 F11 CL2	ASTM A182 F11 CL3	ASTM A182 F12 CL1	ASTM A182 F12 CL2	ASTM A182 F22 CL1	ASTM A182 F22 CL3	ASTM A182 F91
T.S (MPA)	415 min	485 min	515 min	415min	485min	415min	515min	620min
Y.S (MPA)	205 min	275 min	310 min	220min	275min	205min	310min	415min
EL %	20 min	20 min	20 min	20min	20min	20min	20min	20min
R/A %	45 min	30 min	30 min	45min	30min	35min	30min	40min
HARDNESS	121-174	143-207	150-207	121-174	143-207	170	156-207	190-248

MSS SP-97 Weldolet Dimensions

Run pipe Nominal Size		Branch Nominal Size		Length			OD of Fitting			Cut hole Dia.
Run pipe Nominal Size		A			D			d
DN	NPS	DN	NPS	STD	XS	SCH160	STD	XS	SCH	STD	XS	SCH160
8~900	1/4~36	6	1/8	16	16	-	24	24	-	16	16	-
10~900	3/8~36	8	1/4	16	16	-	26	16	-	16	16	-
15~900	1/2~36	10	3/8	19	19	-	30	30	-	19	19	-
20~900	3/4~36	15	1/2	19	19	28	36	36	36	24	24	14
25~900	1~36	20	3/4	22	22	32	43	43	46	30	30	19
32~900	11/4~36	25	1	27	27	38	55	55	51	36	36	25
40~900	11/2~36	32	11/4	32	32	44	66	66	63	45	45	33
50~900	2~36	40	11/2	33	33	51	74	74	71	51	51	38
65~900	21/2~36	50	2	38	38	55	90	90	82	65	65	43
80~900	3~36	65	21/2	41	41	62	104	104	98	76	76	54
90~900	31/2~36	80	3	44	44	73	124	124	122	93	93	73
100~900	4~36	90	31/2	48	48	-	138	138	-	113	113	-
125~900	5~36	100	4	51	51	84	154	154	154	120	120	98
150~900	6~36	125	5	57	57	94	187	187	188	141	141	122
200~900	8~36	150	6	60	78	105	213	227	222	170	170	146
250~900	10~36	200	8	70	99	-	265	292	-	220	220	-
300~900	12~36	250	10	78	94	-	323	325	-	275	265	-
350~900	14~36	300	12	86	103	-	379	381	-	325	317	-
400~900	16~36	350	14	89	10	-	411	416	-	257	361	-
450~900	18~36	400	16	94	106	-	465	468	-	408	403	-
500~900	20~36	450	18	97	111	-	522	525	-	459	455	-
550~900	22~36	500	20	102	119	-	573	584	-	508	509	-
650~900	26~36	600	24	116	140	-	690	708	-	614	612	-

MSS SP 97 Weldolet Weight Chart

DN	NPS	STD	XS	160
6	1/8	0.04	0.05	–
8	1/4	0.04	0.05	–
10	3/8	0.06	0.07	–
15	1/2	0.11	0.13	0.18
20	3/4	0.16	0.18	0.20
25	1	0.32	0.34	0.40
32	1 1/4	0.38	0.42	0.50
40	1 1/2	0.57	0.60	0.70
50	2	0.85	0.90	1.10
65	2 1/2	1.28	1.35	2.00
80	3	1.88	2.00	3.20
90	3 1/2	2.20	2.40	–
100	4	2.80	3.20	6.00
125	5	5.70	6.80	9.80
150	6	7.20	11.0	16.0
200	8	10.8	19.2	31.0
250	10	17.0	19.5	–
300	12	25.6	29.6	–
350	14	27.0	32.0	–
400	16	36.0	41.7	–
450	18	48.2	55.8	–
500	20	58.5	76.0	–
600	24	149	152	–

Main Application Areas

Oil and gas industry: Alloy steel weldolet used in oil and gas extraction, transportation, refining and other links, dealing with high temperature and high pressure, containing hydrogen sulfide, carbon dioxide and other corrosive media pipeline system.

Chemical industry: in a variety of acids, alkalis, salts and other chemical media production and transportation pipeline, resistance to corrosion and high temperature.

Power industry: high-pressure steam piping in thermal power plants, key piping connections in nuclear power plants.

Metallurgical industry: high temperature gas and liquid transportation in blast furnace and steel making equipment.

Aerospace and military industry: fields with very high requirements for material performance.

Offshore engineering: offshore platforms, underwater pipelines and other applications requiring seawater corrosion resistance and high strength.

Comparison with Other Outlet Connection Methods

Connection Type	Advantages	Limitations	Suitable Applications
Weldolet	High pressure resistance, excellent sealing, long service life	Complex welding process, higher cost	High-temperature, high-pressure, or corrosive environments
Threadolet	Easy installation, no welding required	Low pressure resistance (≤PN16), prone to leakage due to vibration	Low-pressure, non-corrosive media
Sockolet	Reduced welding workload, suitable for small-diameter branches	Limited pipe diameter (typically ≤DN50), potential for media accumulation	Small and medium diameter, medium and low pressure pipelines