MSS SP- 97 Weldolet Specification

Z0065c — Wed, 03 Sep 2025 02:00:00 +0000

A MSS SP- 97 Weldolet is a type of branch connection fitting used in piping systems to create a branch connection from a larger main pipe to a smaller pipe or pipeline component. It is designed to provide a smooth transition from the main pipe to the branch pipe, thus facilitating efficient fluid or gas flow while minimizing turbulence.

Specification of MSS SP-97 Weldolet

Standard	MSS-SP-97 Weldolet
Branch Diameter Range	1/8 to 24 inch / DN6-DN600
Pressure Rate	STD, XS, SCH160
Stainless Steel Weldolet	ASTM A182 F304, F304L, F306, F316L, F304H, F309S, F309H, F310S, F310H, F316TI, F316H, F316LN, F317, F317L, F321, F321H, F11, F22, F91, F347, F347H, F454L, ASTM A312/A403 TP304, TP304L, TP316, TP316L
Carbon Steel Weldolet	ASTM/ ASME A 105, ASTM/ ASME A 350 LF 2, ASTM / ASME A 53 GR. A & B, ASTM A 106 GR. A, B & C. API 5L GR. B, API 5L X 42, X 46, X 52, X 60, X 65 & X 70. ASTM / ASME A 691 GR A, B & C
Alloy Steel Weldolet	ASTM / ASME A 182, ASTM / ASME A 335, ASTM / ASME A 234 GR P 1, P 5, P 9, P 11, P 12, P 22, P 23, P 91, ASTM / ASME A 691 GR 1 CR, 1 1/4 CR, 2 1/4 CR, 5 CR, 9CR, 91
Duplex & Super Duplex Steel Weldolet	ASTM A 182 – F 51, F53, F55 S 31803, S 32205, S 32550, S 32750, S 32760, S 32950

MSS SP-97 Standard

Scope

This Standard Practice covers essential dimensions, finish, tolerances, testing, marking, material, and minimum strength requirements for 90 and 45 degree integrally reinforced forged branch outlet fittings of buttwelding, socket welding, and threaded types.

Fittings manufactured to this Standard Practice are designed to make a fully reinforced branch connection in accordance with applicable piping code requirements, when attached, at an opening in a run pipe by means of a full penetration weld.

Fittings may be made to special dimensions, size, shape, tolerances, or of other wrought material by agreement between the manufacturer and the purchaser.

Marking

Each fitting shall be permanently marked with the required identification by raised lettering, and/or by stamping, electroetching or vibro tool.

The marking shall include (but it is not limited to) the following:

a) Manufacturer’s name or trademark.

b) Material Identification The material shall be identified in accordance with the marking requirements of the applicable ASTM Specifications, including Heat Identification.

c) Class The Fitting Class – “STD” (Standard), “XS” (Extra Strong), “SCH 160” (Schedule 160), “3000” or “6000”. Alternatively, the designation 3M or 6M, as applicable, may be used where “M” stands for 1,000.

d) Size The nominal size of the pipe that the fitting’s marking identifies – Run (or consolidated range) NPS (DN) x Outlet NPS (DN).

e) SP-97 This marking indicates compliance with MSS SP-97.

Material & Grades of Weldolet Fittings

Carbon Steel :
ASTM A105 / A105N,ASTM A350 LF2 / LF3, A694 F42 / 46 / 52 / 56 / 65 / 70

Alloy Steel :
ASTM / ASME A/SA 182 & A 387 F1, F5, F9, F11, F12, F22, F91

Stainless Steel :
ASTM A 182, A 240 F 304, 304L, 304H, 316, 316L, 316Ti, 310, 310S, 321, 321H, 317, 347, 347H, 904L

Duplex & Super Duplex Steel :
ASTM / ASME A/SA 182 F 44, F 45, F51, F 53, F 55, F 60, F 61

Copper Alloy Steel :

ASTM SB 61 , SB62 , SB151 , SB152 UNS No. C 70600 (Cu-Ni 90/10), C 71500 (Cu-Ni 70/30), UNS No. C 10100, 10200, 10300, 10800, 12000, 12200

Nickel Alloy :
ASTM SB564, SB160, SB472, SB162 Nickel 200 (UNS No. N02200), Nickel 201 (UNS No. N02201), Monel 400 (UNS No. N04400), Monel 500 (UNS No. N05500), Inconel 800 (UNS No. N08800), Inconel 825 (UNS No. N08825), Inconel 600 (UNS No. N06600), Inconel 625 (UNS No. N06625), Inconel 601 (UNS No. N06601), Hastelloy C 276 (UNS No.N10276), Alloy 20 (UNS No. N08020)

Dimensions Weldolet Size on Size

Run pipe Nominal Size		Branch Nominal Size		Length			OD of Fitting			Cut hole Dia.
Run pipe Nominal Size		Branch 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	–

Weldolets, Sockolets, Threadolets Dimensions & Weights

Referenced Weight Lists Outlet kg
Branch Nominal Size		BW Outlet			SW Outlet		THRD Outlet
DN	NPS	ST D	X S	Sc h 1 6 0	3000	6000	3000	6000
6	1/8	0.04	0.05	–	0.05	–	0.05	–
8	1/4	0.04	0.05	–	0.05	–	0.05	–
10	3/8	.0.06	0.07	–	0.09	–	0.09	–
15	1/2	0.11	0.13	0.18	0.16	0.35	0.17	0.32
20	3/4	0.16	0.18	0.20	0.20	0.47	0.22	0.47
25	1	0.32	0.34	0.40	0.42	0.68	0.43	0.65
32	1 1/4	0.38	0.42	0.50	0.59	1.10	0.61	0.96
40	1 1/2	0.57	0.60	0.70	0.70	1.30	0.69	1.28
50	2	0.85	0.90	1.10	1.10	2.45	1.10	2.15
65	2 1/2	1.28	1.35	2.00	1.40	–	1.52	–
80	3	1.88	2.00	3.20	2.30	–	2.50	–
90	3 1/2	2.20	2.40	–	–	–	–	–
100	4	2.80	3.20	6.00	4.20	–	4.10	–
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	20	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

MSS SP 97 Weldolet ASTM A105,A105N Weldolet

ASTM A105 Weldolet is a pipe branch welding fitting manufactured according to the ASTM A105 carbon steel standard. It is designed for safely welding branch pipes onto main pipelines and is widely used in industrial piping systems for petroleum, chemical, power, and natural gas industries. Featuring excellent mechanical strength, weldability, and pressure resistance, it effectively reduces stress concentration, ensuring reliable branch connections and long-term operational reliability.

Chemical Composition

CHEMICAL	LIMITS	C	Mn	P	S	Si	Cu	Ni	Cr	Mo	V
ASTM A105	MIN		0.60			0.10
ASTM A105	MAX	0.35	1.05	0.035	0.040	0.35	0.40	0.40	0.30	0.12	0.08
ASTM A105N	MIN		0.600
ASTM A105N	MAX	0.350	1.050	0.040	0.050		0.400		0.300	0.120	0.080

Mechanical Property

MATERIAL	T.S (MPA)	Y.S (MPA)	EL %	R/A %	HARDNESS
ASTM A105	485 min	250 min	22 min	30 min	197 max
ASTM A105N	485min	250 min	22 min	30 min	197 max

MSS SP-97 Pipe Weldolet – ASTM A182 F304

Chemical Composition

CHEMICAL	LIMITS	C	Mn	P	S	Si	Ni	Cr	Mo	N
ASTM A182 F304	MIN						8.0	18.0
ASTM A182 F304	MAX	0.08	2.00	0.045	0.030	1.00	11.0	20.0		0.10
ASTM A182 F304H	MIN	0.04					8.00	18.00
ASTM A182 F304H	MAX	0.10	2.00	0.045	0.030	1.00	11.00	20.00
ASTM A182 F304L	MIN						8.00	18.00
ASTM A182 F304L	MAX	0.03	2.00	0.045	0.030	1.00	13.00	20.00		0.10

Mechanical Property

MATERIAL	ASTM A182 F304	ASTM A182 F304H	ASTM A182 F304L
T.S (MPA)	515 min	515 min	485 min
Y.S (MPA)	205 min	205 min	170 min
EL %	30 min	30 min	30 min
R/A %	50 min	50 min	50 min

MSS SP-97 Weldolet, ASTM A182 F22, 3000 LB

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.

Chemical Composition

CHEMICAL	LIMITS	C	Mn	P	S	Si	Ni	Cr	Mo
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

Mechanical Property

MATERIAL	ASTM A182 F22 CL1	ASTM A182 F22 CL3
T.S (MPA)	415min	515min
Y.S (MPA)	205min	310min
EL %	20min	20min
R/A %	35min	30min
HARDNESS	170	156-207

Weldolet Fittings Suppliers

We are a professional supplier of butt weld weldolets, boasting extensive manufacturing experience and a rigorous quality control system. Products are strictly manufactured in accordance with MSS SP-97 or customer-specified standards, utilizing materials including carbon steel, low-alloy steel, and stainless steel. They are suitable for high-pressure piping systems in industries such as petroleum, chemical, power generation, natural gas, and shipbuilding.

Our butt weld weldolets offer the following advantages:

– High-Quality Materials: Premium carbon steel ensures mechanical strength and pressure resistance

– Standardized Dimensions: Strictly customized to MSS SP-97 or client specifications for installation compatibility

– Precision Welding: Flat weld surfaces ensure reliable joints and minimize stress concentration

– Diverse Specifications: Available in various diameters, long/short radii, and 45° or 90° branch configurations

– Timely Delivery: Supports bulk production and expedited shipping to meet urgent project deadlines

Whether for large-scale industrial pipeline projects or customized small-batch requirements, we deliver high-quality, reliable butt-welded branch seat solutions that ensure safe and efficient pipeline system operation.

Differences between Weldolet, Sockolet, and Threadolet

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

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Sockolets – Supplier of Quality Forged Fittings-Flanges

MSS SP- 97 Weldolet Specification

Specification of MSS SP-97 Weldolet

MSS SP-97 Standard

Material & Grades of Weldolet Fittings

Dimensions Weldolet Size on Size

Weldolets, Sockolets, Threadolets Dimensions & Weights

MSS SP 97 Weldolet ASTM A105,A105N Weldolet

MSS SP-97 Pipe Weldolet – ASTM A182 F304

MSS SP-97 Weldolet, ASTM A182 F22, 3000 LB

Weldolet Fittings Suppliers

Differences between Weldolet, Sockolet, and Threadolet