What is Weldolet
The Weldolet is a branch connection fitting used in piping systems to connect branches from a main pipe to smaller pipes or pipe components. It is designed to create a smooth transition between the main pipe and the branch, promoting efficient flow of fluids or gases while minimizing turbulence. The design of the weldolet minimizes stress concentration and provides overall reinforcement. The butt-weld pipe branch is available in three pressure grades: STD, XS and Sch160.
Olet Fittings
A olet provides a branching point from a large-diameter pipe to a smaller-diameter pipe. The pipe welded onto the tee is called the main pipe, while the pipe welded onto the tee is called the branch pipe. Olet fittings come in full sizes, types, bores, and pressure ratings. Materials can include stainless steel, chromium-molybdenum alloy, or other alloy materials.
Olet fittings are providing an outlet from a larger pipe to a smaller one. They are used to instead of connected fittings such as reducing tees, reinforcing plates, and reinforced pipe sections.
There are many types based on the varity piping connected methods that weldolet, thredolet, sockolet, latrolet, elbolet, nipolet, sweepolet and flangolet. Why they are popular, because its outstanding advantages, such as safety, reliability, low cost and simple construction.
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 |
Characteristics of Weldolet Connection
Rational Structure: Butt-welded connections provide a smooth transition between the inside and outside, minimizing fluid resistance.
Reliable Strength: Withstands high pressure and high temperature conditions, offering excellent mechanical properties.
Various Sizes: Flexible branch pipe sizes meet diverse project requirements.
Versatile: Compatible with a variety of materials, including carbon steel, stainless steel, and alloy steel.
MSS SP-97 Weldolet Dimensions
| 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 | – |
Weldolet Weight Table
| Branch Nominal Size | BW Outlet | |||
| DN | NPS | ST D | X S | Sc h 1 6 0 |
| 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 | 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 | |
ASTM A105 Carbon Steel Weldolet
ASTM A105 is a commonly used standard for carbon steel forging materials, employed in the manufacture of various pipe fittings for pipeline systems, including Weldolet. The selection of this material for weldolet primarily leverages the superior properties of carbon steel to meet specific pipeline connection requirements under given operating conditions.
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 |
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 A182 Weldolet
ASTM A182 is a material standard for forged or rolled alloy steel and stainless steel pipe fittings suitable for high-temperature service. Therefore, ASTM A182 butt-welded branch seats serve as an ideal replacement for carbon steel (such as ASTM A105) in applications demanding superior material strength, corrosion resistance, and high-temperature performance.
Alloy Steel
Alloy steel grades specified in the ASTM A182 standard are typically chromium-molybdenum steels (Cr-Mo steels). These grades are made by adding chromium (Cr) and molybdenum (Mo) to improve their high-temperature strength, creep resistance, and corrosion resistance. These steels typically require heat treatment to achieve the desired mechanical properties.
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 | ||||
| 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 | ||||
| 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 | ||||
| MAX | 0.15 | 0.60 | 0.03 | 0.03 | 1.00 | 1.50 | 0.65 | |||
| 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 | |||
| ASTM A182 F91 | MIN | 0.08 | 0.30 | 0.02 | 8.00 | 0.85 | 0.06 | |||
| MAX | 0.12 | 0.60 | 0.02 | 0.01 | 0.50 | 0.40 | 9.50 | 1.05 | 0.10 |
Mechanical Property
| MATERIAL | T.S (MPA) | Y.S (MPA) | EL % | R/A % | HARDNESS |
| ASTM A182 F11 CL1 | 415 min | 205 min | 20 min | 45 min | 121-174 |
| ASTM A182 F11 CL2 | 485 min | 275 min | 20 min | 30 min | 143-207 |
| ASTM A182 F11 CL3 | 515 min | 310 min | 20 min | 30 min | 150-207 |
| ASTM A182 F22 CL1 | 415min | 205min | 20min | 35min | 170 |
| ASTM A182 F22 CL3 | 515min | 310min | 20min | 30min | 156-207 |
| ASTM A182 F91 | 620min | 415min | 20min | 40min | 190-248 |
Stainless Steel
ASTM A182 covers a variety of stainless steel types, including austenitic, ferritic, and martensitic grades. These grades achieve excellent corrosion resistance through the addition of high amounts of chromium (at least 10.5%) to form a passive film.
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 F316 | MIN | 10.0 | 16.0 | 2.00 | ||||||
| MAX | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 14.0 | 18.0 | 3.00 | 0.10 |
Mechanical Property
| MATERIAL | ASTM A182 F304 | ASTM A182 F316 |
| T.S (MPA) | 515 min | 515 min |
| Y.S (MPA) | 205 min | 205 min |
| EL % | 30 min | 30 min |
| R/A % | 50 min | 50 min |
The differences between weldolet, socklet and threadolet
| Feature | Weldolet | Sockolet | Threadolet |
| Connection Type | Butt Weld (welded to run pipe & branch) | Socket Weld (branch pipe inserted into socket) | Threaded (branch pipe screwed into fitting) |
| Pressure Rating | Suitable for high pressure & high temperature | Medium pressure service | Low to medium pressure |
| Size Range | Large range, from small to big bore | Typically for smaller bore connections | Typically for small bore connections |
| Applications | High-pressure pipelines, power plants, refineries, chemical plants | Moderate pressure pipelines, fire-fighting, utility piping | Low-pressure systems, instrument connections |
| Standards | MSS SP-97 | MSS SP-97 | MSS SP-97 |
MSS SP-97 Weldolet Manufacturers and Suppliers
We are a professional supplier of butt weld branch fittings (Weldolet), manufactured strictly in compliance with the MSS SP-97 international standard. Our products are widely used in oil and gas, chemical, power, marine, and pressure pipeline systems. All products undergo rigorous inspection and quality control to ensure customers receive safe, reliable, and durable pipe fitting solutions.