Butt weld pipe fittings

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.

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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.

• 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.

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).

• Concentric reducer is symmetrical both ends are aligned along the center.
• Eccentric reducer is not symmetrical ends are off center of one another.

What is a lateral pipe fitting ?

A 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.