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. | ||||||||
| 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 | ||||||||
| 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 | |||||||||
| 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 | |||||||
| 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 | ||||||
| MAX | 0.10 | 2.00 | 0.045 | 0.030 | 1.00 | 11.00 | 20.00 | |||
| ASTM A182 F304L | MIN | 8.00 | 18.00 | |||||||
| 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 | ||||
| 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 |
