Butt weld pipe fittings

Butt weld pipe fittings allow for changing the direction of flow, reducing pipe sizes and attaching auxiliary equipment.

Common type of Butt weld pipe fittings

A common example using welded pipe fitting is a pipe reduced by concentric reducer, welded to a weld neck flange and connected to an equipment. Figure below represent complete collection of butt welded pipe fitting

Benefits of Butt Weld Pipe Fittings 

The benefit to using a butt weld fitting is that it doesn’t leak. Because the butt weld is welded directly to pipe and not simply bolted together, it is not only much stronger than a typical fitting, but it allows for better flow through the system with less resistance to friction. Welded fittings also allows for better layout designs through key features such as being more compact and greater in strength.

 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.

Materials & Specifications
Material Grade
Carbon Steel WPB, WPC, WPL6
Chrome Moly WP5, WP9, WP11, WP12, WP22
Stainless Steel 304/304L, 316/316L, 304H, 316H, 309, 310S, 317L, 321/321H, 347/347H, 904L, DUPLEX 2205 / SUPER DUPLEX 2507
High Yield Carbon Steel WPHY42, WPHY52, WPHY65
Nickel Alloys Alloy 20, 200, 201, 400, 600, 625, 800H/HT, 825, 254SMO, AL6XN, C276, C22, B3, HAST-X

Forged Steel buttweld fittings are manufactured in accordance with ANSI / ASME B16.9.

Manufacturing Standards of Welded Fittings
Standard Grade
ASME: ANSI B16.9, ANSI B16.28, MSS-SP-43
DIN: DIN2605, DIN2615, DIN2616, DIN2617, DIN28011
EN: EN10253-1, EN10253-2
ASTM A403 – ASME SA403 Standard Specification for Wrought Austenitic Stainless Steel Piping Fittings
ASME B16.9 Factory-Made Wrought Fittings Buttwelding
ASME B16.25 Buttwelding Ends
ASME B16.28 Wrought Steel Short Radius Elbows and Buttwelding Returns
MSS SP-43 Wrought and Fabricated Butt-Welding Fittings for Low Pressure, Corrosion Resistant Applications

Recommended pipe fittings

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Frequently asked questions

These fittings are the most common type of welded pipe fitting and are specified by nominal pipe size and pipe schedule. Buttweld fittings use seamless or welded pipe as the starting material and are forged (through multiple process) to get he shape of elbows, tees and reducers etc.

Pipe Fittings End Beveling
Pipe elbows

Fittings may be made to special dimensions, sizes,shapes, and tolerances by agreement between the manufacturer and the purchaser.

Welding Bevel acc. to
Bevelled Ends

The ends of all buttweld fittings are bevelled, exceeding wall thickness 4 mm for austenitic stainless steel, or 5 mm for ferritic stainless steel. The shape of the bevel depending upon the actual wall thickness. This bevelled ends are needed to be able to make a "Butt weld".

Welding Bevel acc.to ASME / ANSI B16.9 and ASME / ANSI B16.28

ASME B16.25 covers the preparation of buttwelding ends of piping components to be joined into a piping system by welding. It includes requirements for welding bevels, for external and internal shaping of heavy-wall components, and for preparation of internal ends (including dimensions and dimensional tolerances).

Our in-hourse R&D team developed bevel ends equipment are good using in thickness 2mm to 20mm pipe fittings, guarantee high efficiency and high quality.

End bevel

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These weld edge preparation requirements are also incorporated into the ASME standards (e.g., B16.9, B16.5, B16.34).

ASME B16.25 (BUTT WELD ENDS)

ASME B16.25 sets standards for the preparation of the ends of components that need to be welded together.

Asmeb1625

Cut square or slight chamfer, at manufacturer’s option for :

  • t ≤ 0.19” carbon steel or ferritic alloy steels
  • t ≤ 0.12” austenitic alloy steels
Benefits of welded fittings

The allowable pressure ratings for fittings designed in accordance with the standard ASME B 16.9–1993 may be calculated as for straight seamless pipe in accordance with the rules established in the applicable section of the ASME B 31 codes for pressure piping.

  • are strong and leak-proof
  • minimize the pressure drops and the turbolence along the pipeline
  • have a long service life
Buttweld Fittings general

A pipe fitting is defined as a part used in a piping system, for changing direction, branching or for change of pipe diameter, and which is mechanically joined to the system.

There are many different types of fittings and they are the same in all sizes and schedules as the pipe.

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Even welding and smooth weld line, can be substitute for seamless tube after drawing and cold rolling.

ASME B16.9

This Standard covers overall dimensions, tolerances, ratings, testing, and markings for wrought factory-made buttwelding fittings in sizes NPS 1 ⁄ 2 through 48 (DN 15 through 1200).

Fittings may be made to special dimensions, sizes, shapes, and tolerances by agreement between the manufacturer and the purchaser.

ASTM A234/ SA234M

ASTM A234/ SA234M Standard specification for pipe fittings of wrought carbon steel and alloy steel for moderate and high temperature service.

These fittings are for use in pressure piping and in pressure vessel fabrication for service at moderate and elevated temperatures.

Buttweld Pipe Fitting Specification & Standards

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  

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
  1. Fittings made from bar or plate may have 0.35 max carbon.
  2. Fittings made from forgings may have 0.35 max Carbon and 0.35 max Silicon with no min.
  3. 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%.
  4. The sum of Copper, Nickel, Niobium, and Molybdenum shall not exceed 1.00%.
  5. The sum of Niobium and Molybdenum shall not exceed 0.32%.
Stainless Steel Butt Weld Fittings:

Stainless buttweld fittings are available in 316 and 304 grades.

304/304L (UNS S30400/S30403) 

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)         

316/316L (UNS S31600/S31603)  

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 

ASTM A420 WPL6 pipe fittings

The ASTM A420 WPL6 steel pipe fittings means the butt welding pipe fittings whose material is ASTM A420 grade WPL6.ASTM A420 is standard specification for piping fittings of wrought carbon steel and alloy steel for low-temperature service.So A420 WPL6 fittings are specially used in low temperature conditions.

Chemical composition of A420 WPL6 material:

Grade C Mn P S Si
WPL6(1)(2) 0.3 0.60-1.35 0.035 0.04 0.15-0.30

Mechanical properties of A420 WPL6 material:

Tensile Requirements WPL6
Tensile Strength
min, ksi [MPa]
60-85[415-585]
Yield Strength
min, ksi [MPa]
35[240]

ASTM A420 WPL6 pipe fittings are one kind of butt welding pipe fittings,they are commonly produced from the steel pipes of ASTM A333 Grade 6.This material should be arranged the charpy V impact test in temperature of -46℃,to make sure it can work in a lower temperature service,for example in cold weather,winter or deep-sea water offshore projects.

Welded pipe fittings in carbon steel and stainless steel are the joining components that make possible the assembly of valves, pipes and equipment onto the piping system. Welded fittings compliment pipe flanges in any piping system and allows;

  1. Change direction of flow in a piping system
  2. Connect or joint pipes and equipment
  3. Provide branches, access and takeoffs for auxiliary equipment

FITTING SIZES AND DIMENSIONS

Pipe fittings are measured by their diameter, wall thickness (known as “schedule”), and shape or configuration.

Bending
Testing
 Measurement wall thickness
Measurement wall thickness
Measuement out diameter
Measuement out diameter
Ensure the thickness of the outer wall
Ensure the thickness of the outer wall
Protect the end of the bending
Protect the end of the bending
Large size bendings be packed in containers
Large size bendings be packed in containers
How are pipe fittings measured ?
  • (Fittings are also defined by their material grade and whether they are welded or seamless.)
  • Diameter refers to outside diameter of a pipe or fitting.
  • The North American standard is known as Nominal Pipe Size (NPS). The International Standard is known as Diameter Nominal (DN). Pipes and fittings are actually made in similar sizes around the world: they are just labeled differently.
  • From ½ in to 12 inch “Nominal Pipe Size”, outside diameters are slightly larger than indicated size; inside diameters get smaller as schedules grow.
  • From 14 in and larger “Nominal Pipe Size”, outside diameters are exactly as indicated size; inside diameters get smaller as schedules grow.
  • As with other North American standards (inch, foot, yard, mile, …), many pipe standards (diameters up to 12 inch and wall thickness) are based on historical precedents (a toolmaker’s dies during US Civil War) rather than a “scientific” method.

What does “schedule” mean for pipe fittings ?
What is schedule 40, sch80 ?
As the main function of the pipes is to carry fluid under pressure therefore their internal diameter is their critical dimension. This critical dimension is referred to as the nominal bore (NB). Obviously, for pipes containing pressurised fluids the wall thickness, and by implication the pipe’s strength, is important. Wall thickness is expressed in “schedules“, referred to as pipe schedules. The pipe schedule is abbreviated as SCH.

Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures.

  • Schedule, often shortened as sch, is a North American standard that refers to wall thickness of a pipe or pipe fitting. Higher schedules mean thicker walls that can resist higher pressures.
  • Pipe standards define these wall thicknesses: SCH 5, 5S, 10, 10S, 20, 30, 40, 40S, 60, 80, 80S, 100, 120, 140, 160, STD, XS and XXS. (S following a number is for stainless steel. Sizes without an S are for carbon steel.)
  • Higher schedules are heavier, require more material and are therefore more costly to make and install.
Why are fittings sometimes thicker and heavier than pipes to which they are connected ?

Fittings are sometimes thicker than their connecting pipes to meet performance requirements or due to manufacturing reasons.

  • Due to fitting geometry, stress is very different when compared to a pipe.
  • Using extra material is often necessary to compensate for such additional stress, especially for tees and tight curve elbows.
  • Fitting manufacturers may not always stock plates or pipes for all metal grades or sizes.
  • When responding to an order, manufacturers always use the right metal or alloy, but sometimes made with next-higher available plate or pipe size while still respecting specified inside diameters.
What does 45 SR or 90 LR mean for pipe fittings ?

By default, there are 5 opportunities, the 45°, 90° and 180° elbows, all three in the "long radius" version, and in addition the 90° and 180° elbows both in the "short radius" version.

  • 45 and 90 refer to angles for changing direction of pipe flows: 45 degrees or 90 degrees. Most elbows are 45˚ or 90˚.
  • SR means Short Radius; LR means Long Radius. Centerline radius of long radius (LR) elbows is smoother than of short radius (SR).
  • In SR fittings, radius equals nominal diameter size. A 6 inch pipe will have a 6 inch radius center-to-end, giving it a sharp curve.
  • In LR fittings, radius equals 1.5x nominal diameter size. A 6 inch pipe will have a 9 inch centerline radius, for a smoother curve than SR.
What is the difference between a 3R and a 3D elbow?

There is no difference between 3R and 3D.

  • Both have a centerline radius of three times the nominal diameter size.
  • Both have a smoother curve than an SR or LR.
  • (In fittings, 3D does not refer to modeling software or screens.)
What does 3D or 6D mean for pipe fittings ?

Larger numbers have smoother curves.

  • Centerline radius is calculated based on diameter and number that precedes it.
  • For example, a 10″ 6D has a 60″ centerline radius.
  • Smoother curves are often used for applications with higher pressure, abrasion or corrosion.
What is the difference between concentric and eccentric reducers ?

A reducer is the component in a pipeline that reduces the pipe size from a larger to a smaller bore (inner diameter).

What is a lateral pipe fitting ?

lateralA lateral separates one line into two; the second line branches at a 45˚ angle.

The WYE have two branch pipes at a 45 degree angle between them,and the two branch pipes are symmetrical to the centerline of the inflow pipe which means the two outflow direction are both at 22.5 degree to the inflow direction.

What is a seamless butt weld fitting?

A seamless butt weld pipe fitting is made directly from a section of seamless pipe material, by applying heat and pressure to transform pipe directly into an elbow or other shape.

A seamless fitting has no welded parts by itself, a characteristic demanded in some critical applications.
By comparison, a regular butt weld fitting has one, two or more welds, depending on dimension, shape and manufacturing method.

No weld means less risk of weld yield and porosities.

What is PVF?

PVF means Pipe, Valve and Fittings, and is widely used as short-hand to describe this industry.

PVFs can be made in a variety of metals or plastics.

Manufacturers typically specialize in special types of materials; distributors can carry narrow or very broad product lines.

Differentiate between SCH 40 & True Schedule 40

Pipe fittings 12 inch or larger require specifying if fitting is standard wall (most commonly referred to sch 40) or a true schedule 40 is required.

This is needed since schedule 40 do NOT correspond to standard wall for pipe sizes 12” and bigger. A true sch 40 will be thicker than standard wall for pipe fittings 12” or bigger.

Differentiate between SCH 80 & True Schedule 80:
For pipe sizes 10 in and above, sch 80 do NOT correspond to XH. Customer must specify if they want SCH 80 or XH wall.

Fittings applications and markets

Considering the various purposes of pipe fittings, these pipe fittings are used in various industries like:

  • Chemical / Petrochemical
  • Municipal
  • Food, Beverage, and Dairy
  • Oil and Gas
  • Power
  • Process Instrumentation
  • Pulp and Paper
  • Semiconductor
  • Marine & dredging
  • Sanitation



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