What are butt weld fittings?

What are butt weld fittings?

Butt weld fittings are to connect pipes or fittings ends by welding. It’s a weldable steel pipe fitting that would allow to branch off, allow for change of direction of flow, attach auxiliary equipment, or reduce the size of the pipe.
In the case of forged steel butt weld fittings, you would find them to be manufactured according to ANSI/ASME B16.9.
Also known by welded pipe fittings
Butt weld fittings would also be referred to as welded pipe fittings. When these would be used in stainless steel and carbon steel, they would be able to offer certain advantages as compared to socket weld and threaded fittings. Whereas socket weld would only be available up to a specific size, you would find butt weld fittings to be available in sizes starting 1/2 inch to 72 inch.
Like general category of pipe fittings, Butt weld pipe fittings includes:
Butt weld Elbow in 45 degree or 90 degree
Butt weld Tee and Reducing Tee, Reducer, Cap, Cross

Types OF Buttweld Fittings

Pipe elbows
Steel elbow is used to be installed between two lengths of pipe or tube allowing a change of direction,usually these carbon steel elbows distinguished by connection ends.

PIPE ELBOW DIMENSIONS AND SHAPES

Pipe elbows are manufactured in a wide range of dimensions (combinations of outside diameter and wall thickness, i.e. pipe schedule, following the ASME B36.10 and ASME B36.19 sizes specifications for carbon/alloy and stainless steel pipes) to fit the needs of pipelines of sizes from 1 to 80 inches and above (consult the elbows size chart for details). Generally, steel elbows below 24 inches in diameter are produced by cutting and bending seamless steel pipes, and pipe elbows of larger sizes are manufactured using welded pipes or steel plates as feedstock. 

The three most common shapes for pipe elbows are the 45, 90, and 180 degrees (or return elbow), as shown in the image:

20180623105713 64171 - What are butt weld fittings?

Some special types of steel elbows are:

  • reducing elbow: a pipe connector with an inlet and an outlet in two different bore sizes is used instead of the combination of a standard elbow and concentric reducer.
  • mitered elbow: large size elbow assembled by joining steel plates

DIFFERENCE BETWEEN SHORT AND LONG RADIUS PIPE ELBOW

The center to face distance of a long radius pipe elbow (see “B” in the image below) is always 1.5 times the nominal pipe size, whereas, for a short radius pipe elbow, the center to face distance (see “A” in the image) is equal to the nominal pipe size.

Example:

  • For a 4 inches long radius (LR) butt weld elbow, the center to face distance is 4 x 25.4 x 1.5 = 152.4 mm;
  • For a short radius butt weld elbow, the center to face distance is instead 4 x 25.4 x 1 = 101.6 mm. Short radius pipe elbows are available only for the 90 and 180-degree configuration (and not for the 45 degrees); instead, long radius elbows are available for all degrees.

PIPE ELBOW MATERIAL GRADES

The typical material grades for butt weld elbows are carbon steel (ASTM A234 WPA/WPB/WPC), alloy steel for power generation (ASTM A234 WP9/WP91 and other low-alloy grades), stainless steel (ASTM A403 WP304/WP 316 and so on) and, duplex/super duplex (ASTM A815 UNS S31803 and UNS S32750/32760). Nickel alloys like Inconel, Hastelloy, Incoloy are also used to manufacture pipe elbows.

Carbon steel elbows ASTM A234 WPB, WPC – chemical composition:

Grade C Mn P S Si Cr Mo Ni Cu V Nb
WPB 0.3 0.29-1.06 0.05 0.058 0.1min 0.4 0.15 0.4 0.4 0.08 0.02
WPC 0.35 0.29-1.06 0.05 0.058 0.1min 0.4 0.15 0.4 0.4 0.08 0.02

Stainless steel elbows ASTM A403 304, 316 – chemical composition:

Grade C Mn P S Si Ni Cr Mo
WP 304 0.08 2 0.045 0.03 1 8.0-11.0 18.0-20.0
WP 304L 0.035 2 0.045 0.03 1 8.0-13.0 18.0-20.0
WP 316 0.08 2 0.045 0.03 1 10.0-14.0 16.0-18.0 2.00-3.00
WP 316L 0.035 2 0.045 0.03 1 10.0-16.0 16.0-18.0 2.00-3.00

Pipe bending
Pipe bend can be made of variety materials,like carbon steel,alloy steel,stainless steel,low temperature steel or high performance steel,etc.
Pipe Tees
We can provide seamless tube tees and welding tube tees, which can also be divided into straight tees and reducing tees.Usually, the pipe tees have the same inlet and oulet sizes.

There are three main types of pipe tee, equal, reducing, and barred:

EQUAL TEE (STRAIGHT TEE)

An equal tee, otherwise called straight tee, is a butt weld fitting used to branch a pipeline, or any other pipework, at 90 degrees.

20180623110424 15001 - What are butt weld fittings?

A pipe tee is defined “equal” when the bore size at the run and branch sides have the same diameter. An equal tee is therefore used to connect two pipes of the same nominal diameter. To order an equal tee, it is sufficient to provide the nominal diameter, the schedule and the material grade of the pipe tee fitting (sizes should match, of course, the dimension of the connecting pipes).

Equal tees are available in sizes from half an inch to 48 inches (or larger) and in seamless and welded execution (seamless up to 24 inches, welded for tee sizes above 24 inches).

Butt weld tees are manufactured according to ASME B16.9 (carbon and alloy) and MSS SP 43 (stainless steel and nickel alloy). For more information about the materials for steel tees, refer to this article.

REDUCING TEE

A reducing tee features a smaller bore size at the branched pipe side (generally 2/3 sizes smaller). In case a larger bore size reduction is necessary, then a reinforced branch connection (such as a Weldolet) should be preferred to prevent turbulence and have a smoother flow reduction.

20180623110638 24276 - What are butt weld fittings?

The standard dimensions and tolerances of equal and reducing pipe tees are defined by the ASME B16.19 specification (carbon and alloy steel) and by the MSS SP 43 spec (for stainless steel and nickel alloys tees).

BARRED TEE

A barred tee is a special type of equal tee used for pigged pipelines (reducing barred tees do not exist, as the pig would not pass through the reduced area anyways). A barred tee features a welded restriction on the branch pipe side that prevents the pig from flowing from the run pipe into the branched pipe.

20180623110713 15616 - What are butt weld fittings?

Such barred restriction is welded on the internal side of the fitting and looks like a steel cage.

Pipe cross
A pipe fitting, having four openings in the same place, at right angles to each other. A pipe cross is a kind of pipe fitting. It is used in the place where four pipes meet together. The pipe cross may have one inlet and three outlets, or there inlets and one outlet.
End caps
End Cap, Carbon Steel cap, Stainless Steel Caps, ANSI, ISO, JIS and DIN Standards, Measures 1/2 to 56 Inches.
Based on different materials, pipe caps include carbon steel cap, stainless steel cap, and alloy steel cap etc.
Pipe reducer
Pipe reducer are tube fittings that are widely used in a number of industries in order to providing greatest connection flexibility in connecting fractional tubes in various installations.

CONCENTRIC REDUCER

The open ends of a concentric reducer are aligned and centered one to the other. Generally, this type of pipe reducer is used to modify the bore size of the pipeline by two (maximum three) measures, to avoid an excessive pressure drop in the pipeline.

If the required size reduction is larger, a cascade of butt weld fittings (multiple pipe reducers in sequence) has to be used to have a smooth and gradual adjustment of the flow capacity of the pipeline.

ECCENTRIC REDUCER

The open ends of an eccentric reducer are in an “offset” position one to the other. Eccentric reducers are used, generally, for pipelines installed in a horizontal position (whereas concentric reducers are used for pipelines installed vertically or for the inlets of suction pumps, as top flat eccentric reducers).

TOP AND BOTTOM FLAT ECCENTRIC REDUCER

Eccentric reducers can be top flat (“TF”) or bottom flat (“BF”). The bottom flat eccentric reducer type is used for pipe-racks (the bottom of the reducer is flat and at the same level of the bigger sized run pipe), while the top flat pipe reducer type is used at the inlet of piping suction pumps as shown in the image below (this setup prevents the formation of vapor traps in the pipeline):

20180623112032 17084 - What are butt weld fittings?

CONCENTRIC VS ECCENTRIC REDUCER

The key difference between concentric vs eccentric reducer is the centricity of the inlet vs. the outlet of the fitting, which is perfect for a concentric reducer and offset of an eccentric reducer.

Stub end
Stub Ends are fittings used in place of welded flanges where rotating back up flanges are desired. They are also called Lap Joints and Vanstone Flared Laps. A rotating back up flange seats itself against the back surface of the Stub End.

A stub end suits the following applications:

  • All cases that require a rotating back flange to facilitate the bolting activities;
  • High-grade pipelines (stainless steel upwards): the use of stub ends reduces the overall weight of expensive materials in high-grade piping and therefore reduce the overall cost of the flanged connections (savings can be substantial for large diameter or long pipelines). For example, in a stainless steel 316 piping system, the contractor may use stainless steel stud ends (and weld them to the pipes) and carbon steel lap joint flanges (indeed the flange just supports the connection but does not come into contact with the fluid conveyed by the pipeline

It has to be noted that stud ends are becoming popular also in high-pressure applications (whereas they were used for low-pressure applications only in the past).

20180623112414 17444 - What are butt weld fittings?

STUB END TYPES

Stub ends are available in three different types, named “Type A”, “Type B” and “Type C”:

  • The first type (A) is manufactured and machined to match standard lap joint backing flange (the two products have to be used in combination). The mating surfaces have an identical profile to permit a smooth loading of the flare face
  • Stub ends type B are have to be used with standard slip-on flanges
  • Type C stub ends can be used either with lap joint or slip-on flanges and are manufactured from pipes

20180623112841 90967 - What are butt weld fittings?

ASA AND MSS STUB END

Stub ends are available in two different patterns:

  • the short pattern, called MSS-A stub ends
  • the long pattern, called ASA-A stub ends

20180623112932 47568 - What are butt weld fittings?

STUB END FINISH

Stub ends can be ordered with different ends finishing:

  • Beveled Ends
  • Squared Ends
  • Flanged Ends
  • Grooved Ends
  • Threaded Ends (Male Only)

Coupling Fittings
Coupling fittings are used for fluid conduits in which each end portion of two tubes to be connected is provided with a swaged-on adapter carrying the necessary means to connect or disconnect the tubes without disturbing the swaged-on adapter.

PIPE FITTINGS DIMENSIONS AND MATERIALS

Butt weld fittings are manufactured in a wide range of dimensions (combinations of outside diameter and wall thickness, i.e. schedule) and material grades (the most common are ASTM A234 WPB for carbon steel/alloy steel, ASTM A403 WP304 and WP316 for stainless steel wrought fittings, ASTM A815 for duplex and super duplex fittings).

Carbon steel fittings are common for pipelines and process piping applications in the oil and gas and power generation industry, stainless steel fittings are for applications where corrosion and erosion are a key issue (desalination, pharmaceutical and, food sectors).

For specific applications, steel fittings are either coated on the outer surface or internally lined or clad (see the example of an overlay clad tee below).

CARBON AND ALLOY STEEL PIPE FITTINGS: ASTM A234

The ASTM A234 specification covers carbon steel and alloy steel pipe fittings (butt weld) for high-temperature service. A234 WPA, WPC and, WPC fittings match ASTM A53ASTM A106 and, API 5L Gr. B pipes. A234 WP1 to WP91 butt weld fittings match ASTM A335 chrome-moly pipes.

The ASTM A420 specification covers low-temperature carbon steel butt weld fittings to match ASTM A333 Gr.3 and ASTM A333 Gr. 6 pipes; the ASTM A860 specification (WPHY42, WPHY52, WPHY56, WPHY60) covers high yield wrought carbon steel fittings that match high yield API 5L Gr. X42, X52, X56, X60 pipes.

ASTM A234 CHEMICAL COMPOSITION

Chemical composition of ASTM A234 Carbon and Alloy Steel Fittings
Grade C Mn P max S max Si Cr Mo Ni Cu Others
WPB
(1,2,3,4,5)
0.30
max
0.29-1.06 0.050 0.058 0.10
min
0.40
max
0.15
max
0.40
max
0.40
max
V 0.08
max
WPC
(2,3,4,5)
0.35
max
0.29-1.06 0.050 0.058 0.10
min
0.40
max
0.15
max
0.40
max
0.40
max
V 0.08
max
WP1 0.28
max
0.30-0.90 0.045 0.045 0.10-0.50 0.44-0.65
WP12 CL1 0.05-
0.20
0.30-0.80 0.045 0.045 0.60
max
0.80-1.25 0.44-0.65
WP12 CL2 0.05-
0.20
0.30-0.80 0.045 0.045 0.60
max
0.80-1.25 0.44-0.65
WP11 CL1 0.05-
0.15
0.30-0.60 0.030 0.030 0.50-1.00 1.00-1.50 0.44-0.65
WP11 CL2 0.05-
0.20
0.30-0.80 0.040 0.040 0.50-1.00 1.00-1.50 0.44-0.65
WP11 CL3 0.05-
0.20
0.30-0.80 0.040 0.040 0.50-1.00 1.00-1.50 0.44-0.65
WP22 CL1 0.05-
0.15
0.30-0.60 0.040 0.040 0.50
max
1.90-2.60 0.87-1.13
WP22 CL3 0.05-
0.15
0.30-0.60 0.040 0.040 0.50
max
1.90-2.60 0.87-1.13
WP5 CL1 0.15
max
0.30-0.60 0.040 0.030 0.50
max
4.0-6.0 0.44-0.65
WP5 CL3 0.15
max
0.30-0.60 0.040 0.030 0.50
max
4.0-6.0 0.44-0.65
WP9 CL1 0.15
max
0.30-0.60 0.030 0.030 1.00
max
8.0-10.0 0.90-1.10
WP9 CL3 0.15
max
0.30-0.60 0.030 0.030 1.00
max
8.0-10.0 0.90-1.10
WPR 0.20
max
0.40-1.06 0.045 0.050 1.60-
2.24
0.75-1.25
WP91 0.08-
0.12
0.30-0.60 0.020 0.010 0.20-0.50 8.0-9.5 0.85-1.05 0.40
max
V 0.18- 0.25
Nb 0.06-0.10
N 0.03-0.07
Al 0.02 max(6)
Ti 0.01 max(6)
Zr 0.01 max(6)
WP911 0.09-
0.13
0.30-0.60 0.020 0.010 0.10-0.50 8.0-9.5 0.90-1.10 0.40
max
V 0.18-0.25
Nb 0.060-0.10
N 0.04-0.09
Al 0.02 max(6)
B 0.0003-0.006
W 0.90-1.10
Ti 0.01 max(6)
Zr 0.01 max(6)

Notes:

  1. Fittings from bar or plate 0.35 max carbon.
  2. Fittings from forgings 0.35 max Carbon and 0.35 max Silicon with no minimum.
  3. For each reduction of 0.01% below the specified Carbon maximum, an increase of 0.06% Manganese above the specified maximum is permitted, up to a maximum of 1.35%.
  4. The sum of Cu, Ni, Niobium, and Moly shall not exceed 1.00%.
  5. The sum of Niobium and Moly shall not exceed 0.32%.
  6. Applies to heat and product analyses

ASTM A234 MECHANICAL PROPERTIES

Tensile and Yield Strength ASTM A234 for Carbon and Alloy Steel Fittings WPB WPC,

WP11-CL2

WP11-CL1,

WP22-CL1

WP5-CL1

WP9-CL1

WP11-CL3,

WP22-CL3

WP5-CL3

WP9-CL3

WP91
Tensile strength, minimum unless a range is given ksi (MPa) 60 (415) 70 (485) 60 (415) 75 (520) 90 (620)
Yield strength, min ksi (MPa) (0.2% offset or 0.5% extension under-load) 35 (240) 40 (275) 30 (205) 45 (310) 60 (415)

Elongation ASTM A234 for Carbon and Alloy Steel Fittings WPB,
WPC, WP11, WP22
WP91
  Longitud. Transverse Longitud. Transverse
Standard
round specimen, or small proportional specimen, min % in 4 D
22 14 20 13
Rectangular specimen for wall thickness 5/16″ and over, and
for all small sizes tested in full section; min % in 2 in.
30 20
Rectangular specimen for wall thickness less than 5/16″;
min % in 2 in (1/2″ wide specimen)
see note

Note:  For each 0.79 mm decrease in wall thickness below 7.94 mm, a deduction of 1.5 % for longitudinal and 1.0 % for transverse from standard values is permitted

STAINLESS STEEL PIPE FITTINGS: ASTM A403

The ASTM A403 specification covers austenitic stainless steel butt weld fittings to match ASTM A312 TP304, TP316, TP321, etc., pipes.

ASTM A403 CHEMICAL COMPOSITION

 Use scrollbar at the bottom of table.
Chemical Composition of ASTM A403 Stainless Steel
Grade UNS C
strong>(1)
Mn
strong>(1)
P
strong>(1)
S
strong>(1)
Si
strong>(1)
Ni Cr Mo Ti N
strong>(2)
Others
WPXM-19 S20910 0.06 4.0-6.0 0.045 0.030 1.0 11.5-13.5 20.5-23.5 1.50-3.0 0.20-0.40 (3)
WP304 S3040 0.08 2.0 0.045 0.030 1.0 8.0-11.0 18.0-20.0
WP304L S30403 0.030
(4)
2.0 0.045 0.030 1.0 8.0-12.0 18.0-20.0
WP304H S30409 0.04-0.10 2.0 0.045 0.030 1.0 8.0-11.0 18.0-20.0
WP304N S30451 0.08 2.0 0.045 0.030 1.0 8.0-11.0 18.0-20.0 0.10-0.16
WP304LN S30453 0.030 2.0 0.045 0.030 1.0 8.0-11.0 18.0-20.0 0.10-0.16
WP309 S3090 0.20 2.0 0.045 0.030 1.0 12.0-15.0 22.0-24.0
WP310S S3108 0.08 2.0 0.045 0.030 1.0 19.0-22.0 24.0-26.0
WPS31254 S31254 0.020 1.0 0.030 0.010 0.80 17.5-18.5 19.5-20.5 6.0-6.5 0.18-0.22 Cu0.50-1.0
WP316 S3160 0.08 2.0 0.045 0.030 1.0 10.0-14.0 16.0-18.0 2.0-3.0
WP316L S31603 0.030 align=”center”(4) 2.0 0.045 0.030 1.0 10.0-14.0
(5)
16.0-18.0 2.0-3.0
WP316H S31609 0.04-0.10 2.0 0.045 0.030 1.0 10.0-14.0 16.0-18.0 2.0-3.0 0.10-0.16
WP316N S31651 0.08 2.0 0.045 0.030 1.0 10.0-13.0 16.0-18.0 2.0-3.0 0.10-0.16
WP316LN S31653 0.030 2.0 0.045 0.030 1.0 10.0-13.0 16.0-18.0 2.0-3.0 0.10-0.16
WP317 S3170 0.08 2.0 0.045 0.030 1.0 11.0-15.0 18.0-20.0 3.0-4.0
WP317L S31703 0.030 2.0 0.045 0.030 1.0 11.0-15.0 18.0-20.0 3.0-4.0
WPS31725 S31725 0.030 2.0 0.045 0.030 1.0 13.5-17.5 18.0-20.0 4.0-5.0 0.20
WPS31726 S31726 0.030 2.0 0.045 0.030 1.0 13.5-17.5 17.0-20.0 4.0-5.0 0.10-0.20
WPS31727 S31727 0.030 1.0 0.030 0.030 1.0 14.5-16.5 17.5-19.0 3.8-4.5 0.15-0.21 Cu2.8-4.0
WPS32053 S32053 0.030 1.0 0.030 0.010 1.0 24.0-26.0 22.0-24.0 5.0-6.0 0.17-0.22
WP321 S3210 0.08 2.0 0.045 0.030 1.0 9.0-12.0 17.0-19.0 (6)
WP321H S32109 0.04-0.10 2.0 0.045 0.030 1.0 9.0-12.0 17.0-19.0 (7)
WPS33228 S33228 0.04-0.08 1.0 0.020 0.015 0.30 31.0-33.0 26.0-28.0 Ce 0.05-0.10 Al 0.025Nb 0.6-0.10
WPS34565 S34565 0.030 5.0-
7.0
0.030 0.010 1.0 16.0-18.0 23.0-25.0 4.0-5.0 0.40-0.60 Nb 0.10
WP347 S3470 0.08 2.0 0.045 0.030 1.0 9.0-12.0 17.0-19.0 (8)
WP347H S34709 0.04-0.10 2.0 0.045 0.030 1.0 9.0-12.0 17.0-19.0 (9)
WP348 S3480 0.08 2.0 0.045 0.030 1.0 9.0-12.0 17.0-19.0 Nb+Ta= 103(C)-1.10Ta 0.10Co 0.20
WP348H S34809 0.04-0.10 2.0 0.045 0.030 1.0 9.0-12.0 17.0-19.0 Nb+Ta= 83(C)-1.10Ta 0.10Co 0.20
WPS38815 S38815 0.030 2.0 0.040 0.020 5.5-
6.5
13.0-17.0 13.0-15.0 0.75-1.50 Cu 0.75-1.50Al 0.30

Notes:

  1. Maximum, if not otherwise indicated.
  2. The method of analysis for Nitrogen is agreed between the purchaser and manufacturer.
  3. Niobium 0.10-0.30%; Vanadium, 0.10-0.30%.
  4. For small diameter or thin walls, a Carbon maximum of 0.040% is mandatory in grades TP304L and TP316L. Small outside diameter tubes are those less than 0.50 in. [12.7 mm] 5) in outside diameter and light wall tubes as those less than 0.049 in. [1.24 mm] in average wall thickness.
  5. On pierced tubing, the Nickel may be 11.0-16.0%.
  6. 5 X (C+N2)-0.70.
  7. 4 X (C+N2) -0.70.
  8. The Niobium % shall be ten times above the Carbon content and not more than 1.10%.
  9. The Niobium % shall be eight times above the Carbon content and not more than 1.10%.

ASTM A403 MECHANICAL PROPERTIES

Tensile and Elongation Requirements ASTM A403 WP304, WP316 WP304L, WP316L
Yield Strength, min, ksi [MPa] 30 [205] 25 [170]
Tensile Strength, min, ksi [MPa] 75 [515] 70 [485]
Elongation Longitudinal 28 28
Transverse 20 20

DUPLEX AND SUPER DUPLEX PIPE FITTINGS: ASTM A815

The ASTM A815 specification covers duplex and super duplex butt weld fittings to match ASTM A790 and ASTM A928 pipes.

ASTM A815 CHEMICAL COMPOSITION

DUPLEX FITTINGS CHEMICAL COMPOSITION (UNS S31803, UNS S32205)

Grade C Mn Si P S Cr Mo Ni N Fe
S31803 0.030 max 2.00 max 1.00 max 0.030 max 0.020 max 22.0 – 23.0 3.0 – 3.5 4.50 – 6.50 0.14 – 0.20 63.72 min
S32205 0.030 max 2.00 max 1.00 max 0.030 max 0.020 max 21.0 – 23.0 2.50 – 3.50 4.50 – 6.50 0.8 – 0.20 63.54 min

DUPLEX FITTINGS MECHANICAL PROPERTIES (UNS S31803, UNS S32205)

Grades Density (g/cm 3) Density (lb/in 3) Melting Point (°C) Melting Point (°F)
S31803 / S32205 7.805 0.285 1420 – 1465 2588 – 2669

SUPER DUPLEX FITTINGS CHEMICAL COMPOSITION (UNS S32750, UNS S32760)

Grade C Mn Si P S Cr Mo Ni N Fe
S 32750 0.030 max 1.20 max 0.80 max 0.035 max 0.020 max 24.00 – 26.00 3.00 – 5.00 6.00 – 8.00 0.24 – 0.32 58.095 min
S 32760 0.05 max 1.00 max 1.00 max 0.030 max 0.010 max 24.00 – 26.00 3.00 – 4.00 6.00 – 8.00 0.20 – 0.30 57.61 min

SUPER DUPLEX FITTINGS MECHANICAL PROPERTIES  (UNS S32750, UNS S32760)

Grades Density (g/cm 3) Density (lb/in 3) Melting Point (°C) Melting Point (°F)
S32750 / S32760 7.8 0.281 1350 2460

 PIPE FITTINGS MATERIALS MATCHING CHART

The chart shows the matching material grades for ASME B16.9, MSS SP 43 butt weld fittings, ASME B16.11 forged fittings (socket weld and threaded) and steel pipes.

Materials Forged Fittings
Materials
Butt Weld Fittings Materials Steel Pipes Materials
Carbon Steel A181-Gr.1 A181-Gr.2 A234-WPA WPB WPC
Moderate, high temp. service A105-Gr.1 A105-Gr.2 A106-Gr.B/API 5 LB
Low temp. service A350-LF1 A350-LF2 A420-WPL6 A33-Gr.6/A 671
Carbon -1/2 Moly Alloy Steel
High Temp Service A182-F1 A234-WP1
Low Temp Service
1/2Cr-1/2Mo Alloy Steel A182-F2
1/2Cr-1/2Mo-1 Alloy Steel
3/4Cr-1 Mo-3/4NI Alloy Steel
1Cr-1/2Mo Alloy Steel A182-F12 A234-WP12
1Cr-1 Mo-Vd Alloy Steel A404-F24
1-1/4Cr-1/2Mo Alloy Steel A182-F11 A234-WP11
1-1/4Cr-1/2Mo-Vd Alloy Steel
2-1/4Cr-1/2Mo-Vd Alloy Steel A182-F22 A234-WP22
3Cr-1 Mo Alloy Steel A182-F21
5Cr-1/2Mo Alloy Steel A182-F5 A234-WP5
5Cr-1/2Mo-Si Alloy Steel
7Cr-1/2Mo Alloy Steel A182-F7 A234-WP7
9Cr-1 Mo Alloy Steel A182-F9 A234-WP9
13Cr Alloy Steel A182-F6
Stainless Steel 304
Standard A182-F304 A403-WP304 A312-TP304
Low Carbon A182-F304-L A403-WP304-L A312-Tp304L
High Temp Service A182-F304-H A403-WP304-H A312-TP304H
Type 309 Stainless Steel A403-WP309
Type 310 Stainless Steel A182-F310 A403-WP310 A312-TP310
Type 316 Stainless Steel
Standard A182-F316 A403-WP316 A312-TP316
Low Carbon A182-F316-L A403-WP316-L A312-TP316L
High Temp Service A182-F316-H A403-WP316-H A312-TP316H
Type 317 Stainless Steel
Type 321 Stainless Steel
Standard A182-F321 A403-WP321
High Temp Service A182-F321-H A403-WP321-H
Type 347 Stainless Steel
Standard A182-F347 A403-WP347
High Temp Service A182-F347-H A403-WP347-H
Type 348 Stainless Steel
Standard A182-F348 A403-WP348
High Temp Service A182-F348-H
20 Ni-8 Cr Alloy A182-F10

 EUROPEAN VS ASTM PIPE FITTINGS MATERIALS

The table shows the equivalent ASTM and European pipe fittings materials grades.

Butt Weld Fittings Materials Comparison Chart
Werkstoff Number European Grade ASTM Grade
CARBON STEEL FITTINGS MATERIALS
1.0254 St 37.0 S235
– –
1.0305 St 35.8/I P235GH (1.0345) A 234 Grade WPA
1.0305 St 35.8/III P235GH (1.0345)
1.0405 St 45.8/I P265GH (1.0425) A 234 Grade WPB
1.0405 St 45.8/III P265GH (1.0425)
ALLOY STEEL FITTINGS MATERIALS
1.5415 15 Mo 3 16Mo3 A 234 Grade WP1
1.7335 13 CrMo 4 4 13CrMo4-5 A 234 Grade WP11, WP12
1.7380 10 CrMo 9 10 10CrMo9-10 A 234 Grade WP22
1.7362 12 CrMo 19 5 X11CrMo5 A 234 Grade WP5
– – A 234 Grade WP9
1.4903  – X10CrMoVNb9-1 A 234 Grade WP91
LOW TEMPERATURE CARBON STEEL FITTINGS MATERIALS
1.5637 10 Ni 14 12Ni14 A 420 Grade WPL3
1.0356 TTSt 35 N P215NL (1.0451)
1.0356 TTSt 35 V
– – A 420 Grade WPL6
HIGH YIELD CARBON STEEL FITTINGS MATERIALS
– –
1.0486 StE 285 A 860 Grade WPHY42
1.0562 StE 355 P355N A 860 Grade WPHY52
1.8902 StE 420 A 860 Grade WPHY60
1.8905 StE 460 A 860 Grade WPHY70
HIGH YIELD CARBON STEEL FITTINGS MATERIALS
1.0457 StE 240.7
1.0484 StE 290.7 L290NB A 860 Grade WPHY42
1.0582 StE 360.7 L360NB A 860 Grade WPHY52
1.8972 StE 415.7 L415NB A 860 Grade WPHY60
– –
STAINLESS STEEL FITTINGS MATERIALS
1.4541 X 6 CrNiTi 18 10 X6CrNiTi18-10 A 403 Grade WP321
1.4571 X 6 CrNiMoTi 17 12 2 X6CrNiMoTi17-12-2 A 403 Grade WP316Ti
1.4301 X 5 CrNi 18 10 X5CrNi18-10 A 403 Grade WP304
1.4306 X 2 CrNi 19 11 X2CrNi19-11 A 403 Grade WP304L
1.4307  – X2CrNi18-9 A 403 Grade WP304L
1.4401 X 5 CrNiMo 17 12 2 X5CrNiMo17-12-2 A 403 Grade WP316
1.4404 X 2 CrNiMo 17 13 2 X2CrNiMo17-12-2 A 403 Grade WP316L
1.4462 X 2 CrNiMoN 22 5 3 X2CrNiMoN22-5-3 UNS S 31803 (Duplex)
1.4529 X 1 NiCrMoCuN 25 20 6 X1NiCrMoCuN25-20-7 UNS N 08926
1.4539 X 1 NiCrMoCuN 25 20 5 X1NiCrMoCu25-20-5 UNS N 08904 (904L)
1.4547  – X1CrNiMoCuN20-18-7 UNS S 31254

SEAMLESS VS WELDED FITTINGS

Butt weld fittings are available in seamless and welded execution (seamless for bore sizes below 24 inches, welded for sizes above 24 inches). They are manufactured, respectively, using seamless pipes (butt weld fittings <24 inches), welded pipes (butt weld fittings >24 inches) or steel plates (large diameter fittings, like metered ones).

  • Seamless butt weld pipe fittings are manufactured using sections of seamless pipes and applying heat and pressure that shapes the tube into a pipe fitting shape
  • A seamless butt weld fitting has no welding, which is a requirement in some high pressure and high-temperature applications. The absence of welds and the related porosities guarantees strength, durability and superior mechanical performance (the pipe fitting is less prone to corrosion attacks)
  • A welded butt weld fitting has one, two or more welds, depending on dimension, the required shape and manufacturing process

INDUSTRIES USING BUTT WELD FITTINGS

Butt weld fittings are used in any industry where liquids, gases, chemicals and other fluids are used (manufactured, transported, distributed, processed), such as:

  • Oil & Gas: Oil and gas industry, including upstream, midstream (transportation, storage, and local distribution) and downstream (petrochemical refining).
  • Power generation: Power plants of any nature, thermal, fossil, nuclear
  • Desalination: Plants to produce drinkable water from seawater
  • Food and beverage
  • Pharma
  • Semiconductors
  • Pulp and paper
  • Construction industry

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”.

20180623104337 63689 - What are butt weld fittings?

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

FITTINGS APPLICATIONS AND MARKETS
Fittings are used wherever liquids, gases, chemicals and other fluids are created, processed, transported, or used. Range of industries is very wide, as shown below:

  • Energy related. Oil and gas industries, including upstream (exploration and production), midstream (transportation by ships, pipeline, rail, trucks; storage and wholesale) and downstream (refining into fuels or chemicals; marketing and distribution). Power plants using fossil or nuclear fuels. Geothermal energy for harnessing heat from the earth.
  • Food and beverage production. From basic ingredients to elaborate desserts. From milk, to juices and other beverages. Cold chain to keep produce fresh, drinks and frozen foods at a set temperature. Desalination plants to transform seawater into drinking water for arid areas and various tropical islands.
  • Pharmaceuticals and biotech production. Medicines and vaccines that treat illnesses and help restore bodies and minds to their top conditions.
  • Semiconductor manufacturing: Microchips that go into all electronics, including smartphones, tablets, computers, television sets, telecom networks, …
  • Pulp and paper production. Newsprint, glossy paper, cardboard boxes, books, writing paper, …
  • Production of construction materials and plastics. From roofing materials, to glassmaking for windows, to copper wiring for transporting electricity, and various plastics throughout houses and office buildings.

DESTRUCTIVE AND NON-DESTRUCTIVE TESTING

Why and how often are pipe fittings tested ?

  • Pipe fittings are tested to assure conformity with standards and performance in their applications.
  • Standard, commodity fittings are tested by sampling during manufacturing process, with both destructive and non-destructive approaches.
  • Custom-made fittings are regularly tested during manufacturing process with non-destructive approaches, as required for the application or as specified by end-users.

What is the difference between a destructive and a non-destructive test ?

  • After a destructive test, fittings can no longer be used in the field, because they were bent, pulled or abused until breakage point. For this reason, destructive tests can only be performed on a small sample of fittings; otherwise, all fittings would be destroyed during tests.
  • non-destructive test measures performance for regular operating conditions, or by means that do not destroy the fitting.

What are most frequent destructive tests for fittings?

  • Bending: fittings are bent until deformation appears on their side, face or root.
  • Charpy impact: named after Georges Charpy who developed it, this test measures toughness of a fitting by determining the amount of energy absorbed during its fracture from impacts.
  • Corrosion: fittings are exposed to corrosive fluids or materials until corrosion appears.
  • Metallographic: this test studies physical structure and components of metal samples, typically by microscopy. Samples are taken from actual fittings.
  • Tension: fittings are stretched until deformation appears; measures are taken for strength, yield, elongation.

What are most frequent non-destructive tests for fittings?

  • Dye or liquid penetrant: low-cost test to detect surface hairline cracks or porosity in fittings, by applying a special liquid to its surface.
  • Ferrite content: ferrite content in Duplex, Super Duplex and stainless steel has to be just right to achieve yield strength, fracture toughness and corrosion resistance. Ferrite content is measured in weld seams by magnetic induction.
  • Hydrostatic: a fitting is filled with a liquid, often colored water, and pressure is applied; measurements are taken to see if there is pressure loss due to any defects.
  • Magnetic particles: uses a magnetic field to detect surface or slightly subsurface discontinuity or weakness in a fitting.
  • Macrography: makes photographs, sometimes in 3 dimensions, of items visible to naked eye.
  • Micrography: uses microscopes to make photographs of metal and obtain information about its properties.
  • Pneumatic pressure: a fitting is filled with pressurized air; measurements are taken to see if there is pressure loss due to any defects.
  • Positive material identification: analysis of a metal alloy by identifying percentage for each of its elements. Uses specialty equipment, including X-ray fluorescence or optical emission spectrometry.
  • Radiography: uses X-rays or gamma rays to detect any weakness in fittings.

How a butt weld fitting is made
This kind of pipe fitting would be made by a process known as hot forming. This would include bending the pipe and then forming it in to a shape. The starting material of this fitting would be a pipe that would first be cut in to length. This would then be heated and molded in to specific shapes with the help pf dies. In addition, heat treatment would also be done in order to get the desired mechanical properties and removed residual stresses.
Benefits of butt weld fittings

  • The welded connection would help to get more robust connection.
  • Continuous structure of metal would add to the strength of the piping system.
  • When butt weld fittings would be matched with the appropriate pipe schedules, they would help to offer a seamless flow inside the pipe.
  • It provides the option of various turn radius by using Long Radius, Short Radius, or 3R elbows.
  • Found to be cost effective compared to the socket weld or threaded counterparts.
  • These fittings would be available in Schedule 10, thus allowing for a thinner wall option.
  • These fittings have been found to be more common in the configuration of Schedule 10 and Schedule 40.
  • Butt weld fittings have beveled ends treatment.

All of the butt weld fittings would have beveled ends as per ASME B16.25 standards. This would help to create a full penetration with requiring any extra preparation.
These kinds of fittings would most commonly be used in cases of stainless steel, carbon steel, alloy steel, aluminum, nickel, and high yield material.

Source: China Butt Weld Fttings Manufacturer – Yaang pipe fitting Industry Co., Limited (www.ugsteelmill.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@ugsteelmill.com

Please notice that you might be interested in the other technical articles we’ve published:

References:

  • https://www.yaang.com

Related News

العربيةБългарски简体中文繁體中文DanskNederlandsEnglishFrançaisDeutschBahasa IndonesiaItaliano日本語한국어LatinPortuguêsРусскийEspañolதமிழ்ไทยTürkçe