All welded pipe fittings have bevelled ends to allow for ease of welding. This bevel allows for full penetration weld in most cases. There are two types of bevels;
Plain Bevel and Compound Bevel.
Welded pipe fittings are made as per ASME spec B16.9. ASME B16.9 covers factory made wrought steel butwelding fittings in sizes 1/2" to 48". This standard however does not cover low pressure corrosion resistant buttwelding fittings. See MSS SP-43, Wrought Stainless Steel Butt-Welding Fittings.
A234 WPB is the most common material used for carbon steel butt welded fittings.
ASTM A234 WPB is the Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service.
Specifications
ASTM: A234 WPB
ASME: B16.9, B.11
NACE: MRO175
MSS: SP-83, SP-95
Chemical Composition%
Grade | C | Mn | P | S | Si | Cr | Mo | Ni | Cu | Others |
– | – | – | max | max | – | – | – | – | – | – |
WPB | 0.3 | 0.29-1.06 | 0.05 | 0.058 | 0.1 | 0.4 | 0.15 | 0.4 | 0.4 | V 0.08 |
(1,2,3,4,5) | max | – | – | – | min | max | max | max | max | max |
Fittings made from bar or plate may have 0.35 max carbon.
Fittings made from forgings may have 0.35 max Carbon and 0.35 max Silicon with no min.
For each reduction of 0.01% below the specified Carbon maximum, an increase of 0.06% Manganese above the specified maximum will be permitted, up to a maximum of 1.35%.
The sum of Copper, Nickel, Niobium, and Molybdenum shall not exceed 1.00%.
The sum of Niobium and Molybdenum shall not exceed 0.32%.
Stainless buttweld fittings are available in 316 and 304 grades.
Chemical Composition%
C | Cr | Mn | Ni | P | S | Si |
MAX | – | MAX | – | MAX | MAX | MAX |
0.035 | 18.0- 20.0 | 2.00 | 8.0-13.0 | 0.045 | 0.030 | 1.00 |
Tensile Requirements
Tensile Strength: (KSI) = 60
Yield Strength: (KSI) = 35
(KSI converts to MPA {Megapascals} by multiplying by 6.895)
Chemical Composition%
C | Cr | Mn | Mo | Ni | P | S | Si |
MAX | – | MAX | – | Max | MAX | MAX | |
0.035 | 16.0- 18.0 | 2.00 | 2.0-3.0 | 10.0-14.0 | 0.045 | 0.030 | 1.00 |
Tensile Requirements
Tensile Strength: (KSI) = 70
Yield Strength: (KSI) = 25
(KSI converts to MPA {Megapascals} by multiplying by 6.895)
A butt weld pipe fitting is made by the process of hot forming that includes bending and forming to shape. The starting material of butt weld fitting is a pipe that is cut to length, heated and molded into specific shapes by means of dyes. Heat treatment is also done to remove residual stresses and obtain desired mechanical properties. Read the link here to get more in depth detail of butt weld fitting manufacturing.
Welded connection offers a more robust connection
Continuous metal structure adds to the strength of the piping system
Buttweld fittings with matching pipe schedules, offers seamless flow inside the pipe. A full penetration weld and properly fitted LR 90 Elbow, Reducer, Concentric reducer etc. offers gradual transition via welded pipe fitting.
Option of various turn radius using Short Radius (SR), Long Radius (LR) or 3R Elbows
Cost effective compared to their expensive threaded or socket weld counter parts.
Stainless Steel Welded Fittings are also available in SCH 10, allowing a more thinner wall option.
Stainless Steel Butt Weld Fittings are more common in SCH 10 and SCH 40 configuration.
All butt weld fittings have beveled ends as per ASME B16.25 standard. This helps create full penetration weld without any extra preparation needed for the butt weld fitting.
Butt weld pipe fittings are most commonly available in carbon steel, stainless steel, nickel alloy, aluminum and high yield material. High yield butt weld carbon steel pipe fittings are available in A234-WPB, A234-WPC, A420-WPL6, Y-52, Y-60, Y-65, Y-70. All WPL6 pipe fittings are annealed and are NACE MR0157 and NACE MR0103 compatible.
