Stub End Manufacturer

A stub end is a type of pipe fitting used in various industrial applications to connect pipes or flanges.

It is designed to be welded to the pipe or lap joint flange, providing a secure and leak-proof joint. The stub end itself does not have any threading; instead, it acts as a sleeve that slips over the pipe or lap joint flange. This unique design allows for easy and quick disassembly of the joint when needed.

Types of Stub Ends

Stub end are offered in three different ways, type A, B and C. Type A and B stub end are similar to forged fittings, such as elbows and tees, and type C stub end are made in customized sizes.

Stainless U bend tubes

Stub ends are manufactured in three different types and two standard length.

Type “A”: this type is produced and machined to fit lap joint flanges.The mating surfaces of the stub end and the lap joint flange have a matching profile and surface. The lap thickness of type A stub ends is > = the minimum wall thickness of the connected pipe. The outside the stub end and the lap joint flange have a matching profile and surface. The lap thickness of type A stub ends is > = the minimum wall thickness of the connected pipe. The outside corner of type A has a radius to accommodate the lap join flange, whereas the inside corner is squared.

Type “B”: this type of stub ends is suited for standard slip-on flanges acting as lap-joint flanges. The lap thickness of type B stub ends is >= the minimum WT of the connecting pipe. The lap of these type of stub ends has generally a serrated face. To ensure tight joints, chamfers on the ID side of the flange are required.

Type “C”: this last type can be used both with lap joint and slip-on backing flanges and are fabricated out of pipes. The lap of C-type stub ends is flared over and the lap thickness is 75% of the connecting pipe WT. Type C has a short fillet outer radius able to host any back up flange.

Type “CS”: this type is similar to “C” with the difference that the lap face has concentric serrations machined during the manufacturing process.

Stub end

Common Types and Lengths

There are two main types of stub ends commonly used in piping systems:

  1. Long Pattern Stub End: A long pattern stub end has a longer length compared to the pipe it is attached to. It is designed to be used with standard lap joint flanges. The long pattern allows for easier alignment and welding of the lap joint flange, making it suitable for applications where frequent disassembly is required.
  2. Short Pattern Stub End: A short pattern stub end has a length that is similar to the pipe it is connected to. It is used with slip-on flanges, where the stub end slides over the pipe and is welded in place. The short pattern stub end is ideal for applications where space is limited, and the flange needs to be close to the end of the pipe.

Both long pattern and short pattern stub ends are available in various materials such as stainless steel, carbon steel, alloy steel, and others, making them suitable for different industrial applications. They provide a cost-effective and reliable solution for connecting pipes to flanges in piping systems.

Stub ends dimensions and weight

Dimensions and manufacturing tolerances are covered in ASME B16.9 – Butt Weld Fittings and MSS-SP-43 (JIS B2312, JIS B2313 may also apply).

Stub End come in three standard lengths, MSS SP43 or ANSI B16.9 short and long pattern. Short pattern stub ends are mostly used for flanges from class 300 to class 600 and above. Besides these standard types, End-Users and contractors can require stub ends with non-standard lengths to suit specific project’s requirement. This will of course come at an additional cost.

Ends face lap finishing

Ends/Face lap finishing

ASME B16.25 END WELDING BEVEL as right

The following types of ends may be ordered:

Beveled Ends (generally ASME B16.25)
Squared Ends
Flanged Ends
Victaulic Grooves
Threaded Ends (Male Only)


Standard

Pipe fitting dimensions are in either metric or Standard English.

Because pipe fitting covers Pipe Fitting Dimensions several aspects, only the most common pipe fitting sizes can be given here. The most applied version is the 90° long radius and the 45° elbow, while the 90° short radius elbow is applied if there is too little space. The function of a 180° elbow is to change direction of flow through 180°. Both, the LR and the SR types have a center to center dimension double the matching 90° elbows. These fittings will generally be used in furnesses or other heating or cooling units.

Some of the standards that apply to buttwelded fittings are listed below. Many organizations such as ASME, ASTM, ISO, MSS, etc. have very well developed standards and specifications for buttwelded fittings. It is always up to the designer to ensure that they are following the applicable standard and company specification, if available, during the design process.

Some widely used pipe fitting standards are as follows:

ASME: American Society for Mechanical Engineers
This is one of the reputed organizations in the world developing codes and standards.
The schedule number for pipe fitting starts from ASME/ANSI B16. The various classifications of ASME/ANSI B16 standards for different pipe fittings are as follows:

ASTM International: American Society for Testing and Materials
This is one of the largest voluntary standards development organizations in the world. It was originally known as the American Society for Testing and Materials (ASTM).

AWWA: American Water Works Association

AWWA About – Established in 1881, the American Water Works Association is the largest nonprofit, scientific and educational association dedicated to managing and treating water, the world’s most important resource.

ANSI: The American National Standards Institute

ANSI is a private, non-profit organization. Its main function is to administer and coordinate the U.S. voluntary standardization and conformity assessment system. It provides a forum for development of American national standards. ANSI assigns “schedule numbers”. These numbers classify wall thicknesses for different pressure uses.

MSS STANDARDS: Manufacturers Standardization Society
The Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry is a non-profit technical association organized for development and improvement of industry, national and international codes and standards for: Valves, Valve Actuators, Valve Modification, Pipe Fittings, Pipe Hangers, Pipe Supports, Flanges and Associated Seals

Difference between “Standard” and “Codes”:

Piping codes imply the requirements of design, fabrication, use of materials, tests and inspection of various pipe and piping system. It has a limited jurisdiction defined by the code. On the other hand, piping standards imply application design and construction rules and requirements for pipe fittings like adapters, flanges, sleeves, elbows, union, tees, valves etc. Like a code, it also has a limited scope defined by the standard.

Factors affecting standards: “Standards” on pipe fittings are based on certain factors like as follows:

BSP: British Standard Pipe

BSP is the U.K. standard for pipe fittings. This refers to a family of standard screw thread types for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread. This has been adopted internationally. It is also known as British Standard Pipe Taper threads (BSPT )or British Standard Pipe Parallel (Straight) threads (BSPP ). While the BSPT achieves pressure tight joints by the threads alone, the BSPP requires a sealing ring.

JIS: Japanese Industrial Standards

This is the Japanese industrial standards or the standards used for industrial activities in Japan for pipe, tube and fittings and published through Japanese Standards Associations.

NPT: National Pipe Thread

National Pipe Thread is a U.S. standard straight (NPS) threads or for tapered (NPT) threads. This is the most popular US standard for pipe fittings. NPT fittings are based on the internal diameter (ID) of the pipe fitting.

BOLTS & NUTS

We are manufacturer of Flange bolts & Nuts and supply high quality

AN: Here, “A” stands for Army and “N” stands for Navy

The AN standard was originally designed for the U.S. Military. Whenever, a pipe fitting is AN fittings, it means that the fittings are measured on the outside diameter of the fittings, that is, in 1/16 inch increments.

For example, an AN 4 fitting means a fitting with an external diameter of approximately 4/16″ or ¼”. It is to be noted that approximation is important because AN external diameter is not a direct fit with an equivalent NPT thread.

Dash (-) size

Dash size is the standard used to refer to the inside diameter of a hose. This indicates the size by a two digit number which represents the relative ID in sixteenths of an inch. This is also used interchangeably with AN fittings. For example, a Dash “8” fitting means an AN 8 fitting.

ISO: International Organization for Standardization

ISO is the industrial pipe, tube and fittings standards and specifications from the International Organization for Standardization. ISO standards are numbered. They have format as follows:

“ISO[/IEC] [IS] nnnnn[:yyyy] Title” where

General standard

Standard Specification
ASTM A234 Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
ASTM A420 Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Low-Temperature Service
ASTM A234 WPB ASTM A234 is Standard Specification for steel pipe fittings includes carbon and alloy steel material for moderate and high temperature services. WPB is one of the steel grade in this standard
ASME B16.9 ASME B16.9 Standard covers overall dimensions, tolerances,ratings, testing, and markings for factory-made wrought buttwelding fittings in sizes NPS 1⁄2 through NPS 48 (DN 15 through DN 1200).
ASME B16.28 ASME B16.28 Standard covers ratings, overall dimensions, testing, tolerances, and markings for wrought carbon and alloy steel buttwelding short radius elbows and returns.
MSS SP-97 MSS SP-97 Standard Practice covers essential dimensions, finish, tolerances, testing, marking, material, and minimum strength requirements for 90 degree integrally reinforced forged branch outlet fittings of buttwelding, socket welding, and threaded types.
ASTM A403 Standard Specification for Wrought Austenitic Stainless Steel Piping Fittings.

Wide variety for all areas of application

DIN EN ASME
St 35.8 I
St 35.8 III
15 Mo 3
13 CrMo 4 4
10 CrMo 9 10
St 35 N
St 52.0
St 52.4
P235GH-TC1
P235GH-TC2
16Mo3
13CrMo4-5
10CrMo9-10
X10CrMoVNb9-1
P215NL
P265NL
L360NB
L360NE
P355N
P355NL1
P355NH
WPB
WPL6
WPL3
WPHY 52
WP11
WP22
WP5
WP9
WP91
WP92
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Chemical Composition (%) of ASTM A234/A234M

Grade Type C Si S P Mn Cr Ni Mo Other ób ós δ5
WPB 0.3 0.1min 0.058 0.05 0.29-1.06 0.4 0.4 0.15 V:0.06;Nb:0.02 415-585 240 22 197
WPC 0.35 0.1min 0.058 0.05 0.29-1.06 0.4 0.4 0.15 V:0.06;Nb:0.02 485-655 275 22 197
WP1 0.28 0.1-0.5 0.045 0.045 0.3-0.9 0.44-0.65 380-550 205 22 197
WP12 CL1 0.05-0.2 0.6 0.045 0.045 0.3-0.8 0.8-1.25 0.44-0.65 415-585 220 22 197
WP12 CL2 0.05-0.2 0.6 0.045 0.045 0.3-0.8 0.8-1.25 0.44-0.65 485-655 275 22 197
WP11 CL1 0.05-0.15 0.5-1 0.03 0.03 0.3-0.6 1-1.5 0.44-0.65 415-585 205 22 197
WP11 CL2 0.05-0.2 0.5-1 0.04 0.04 0.3-0.8 1-1.5 0.44-0.65 485-655 275 22 197
WP11 CL3 0.05-0.2 0.5-1 0.04 0.04 0.3-0.8 1-1.5 0.44-0.65 520-690 310 22 197
WP22 CL1 0.05-0.15 0.5 0.04 0.04 0.3-0.6 1.9-2.6 0.87-1.13 415-585 205 22 197
WP22 CL3 0.05-0.15 0.5 0.04 0.04 0.3-0.6 1.9-2.6 0.87-1.13 520-690 310 22 197
WP5 CL1 0.15 0.5 0.03 0.04 0.3-0.6 4-6 0.44-0.65 415-585 205 22 217
WP5 CL3 0.15 0.5 0.03 0.04 0.3-0.6 4-6 0.44-0.65 520-690 310 22 217
WP9 CL1 0.15 1 0.03 0.03 0.3-0.6 8-10 0.9-1.1 415-585 205 22 217
WP9 CL3 0.15 1 0.03 0.03 0.3-0.6 8-10 0.9-1.1 520-690 310 22 217
WPR 0.2 0.05 0.045 0.4-1.06 1.6-2.24 435-605 315 22/28 217
WP91 0.08-0.12 0.2-0.5 0.01 0.02 0.3-0.6 8-9.5 0.4 0.85-1.05 See sdandard 585-760 415 20 248
WP911 0.09-0.13 0.1-0.5 0.01 0.02 0.3-0.6 8.5-10.5 0.4 0.9-1.1 See sdandard 620-840 440 20 248

Notes:

For each reduction of 0.01% below the specified C maximum, an increase of 0.06% Mn above the specified maximum will be permitted, up to a maximum of 1.35%.

The sum of Cu, Ni, Cr, and Mo shall not exceed 1.00%.

The sum of Cr and Mo shall not exceed 0.32%.

The maximum carbon equivalent (C.E.) shall be 0.50, based on heat analysis and the formula C.E.=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15.

Mechanical properties of ASTM A234

Tensile Requirements WPB WPC, WP11CL2 WP11CL1  WP11CL3
Tensile Strength, min, ksi[MPa]
(0.2% offset or 0.5% extension-under-load)
60-85
[415-585]
70-95
[485-655]
60-85
[415-585]
 75-100
[520-690]
Yield Strength, min, ksi[MPa] 32
[240]
40
[275]
30
[205]
45
[310]

What is the ASTM A403?

ASTM A403 Stainless Steel Pipe Fittings refers to the material of forged and rolled austenitic stainless fittings for pressure pipes. Common grades are WP304/L, WP316/L. They can be used into many fields as engineering industry, energy conversion plants etc.

ASTM A403 Standard specification covers the standard for wrought austenitic stainless steel fittings for pressure piping applications.

ASTM A403/ WP304L Stainless Steel Pipe Elbow

ASTM A403 WP304L Stainless Steel Pipe Elbow

90 Degree A403 Stainless elbow

90 Degree A403 Stainless elbow

Chemical Composition (%) of ASTM A403

Steel No. Type C Si S P Mn Cr Ni Mo Other ób ós δ5
WP304 0.08 1 0.03 0.045 2 18-20 8-11 515 205 28
WP304H 0.04-0.1 1 0.03 0.045 2 18-20 8-11 515 205 28
WP304L 0.035 1 0.03 0.045 2 18-20 8-13 485 170 28
WP304LN 0.03 0.75 0.03 0.045 2 18-20 8-10.5 N2:0.1-0.16 515 205 28
WP304N 0.08 0.75 0.03 0.045 2 18-20 8-11 N2:0.1-0.16 550 240 28
WP309 0.15 1 0.03 0.045 2 22-24 12-15 515 205 28
WP310 0.15 1.5 0.03 0.045 2 24-26 19-22 515 205 28
WP316 0.08 1 0.03 0.045 2 16-18 10-14 2-3 515 205 28
WP316H 0.04-0.1 1 0.03 0.045 2 16-18 10-14 2-3 515 205 28
WP316LN 0.03 0.75 0.03 0.045 2 16-18 11-14 2-3 N2:0.1-0.16 515 205 28
WP316L 0.035 1 0.03 0.045 2 16-18 10-16 2-3 485 170 28
WP316N 0.08 0.75 0.03 0.045 2 16-18 11-14 2-3 N2:0.1-0.16 550 240 28
WP317 0.08 1 0.03 0.045 2 18-20 11-15 3-4 515 205 28
WP317L 0.03 1 0.03 0.045 2 18-20 11-15 3-4 515 205 28
WP321 0.08 1 0.03 0.045 2 17-20 9-13 Ti:5C-0.7 515 205 28
WP321H 0.04-0.1 1 0.03 0.045 2 17-20 9-13 Ti:4C-0.7 515 205 28
WP347 0.08 1 0.03 0.045 2 17-20 9-13 Nb+Ta:10C-1.1 515 205 28
WP347H 0.04-0.1 1 0.03 0.045 2 17-20 9-13 Nb+Ta:8C-1 515 205 28
WP348 0.08 1 0.03 0.045 2 17-20 9-13 Ta:0.1 515 205 28
WP348H 0.04-0.1 1 0.03 0.045 2 17-20 9-13 Ta:0.1 515 205 28

Notes:

For each reduction of 0.01% below the specified C maximum, an increase of 0.06% Mn above the specified maximum will be permitted, up to a maximum of 1.35%.

The sum of Cu, Ni, Cr, and Mo shall not exceed 1.00%.

The sum of Cr and Mo shall not exceed 0.32%.

The maximum carbon equivalent (C.E.) shall be 0.50, based on heat analysis and the formula C.E.=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15.

Mechanical properties of ASTM A403

Grade UNS Tensile Strength, min Yield Strength,min Elongation min % in 4D
ksi MPa ksi MPa Longit % Trans%
ALL ALL 75 515 30 205 28 20
304L S30403 70 485 25 170 28 20
316L S31603 70 485 25 170 28 20
304N S30451 80 550 35 240 28 20
316N S31651 80 550 35 240 28 20
S31726 80 550 35 240 28 20
XM-19 S20910 100 690 55 380 28 20
S31254 94-119 650-820 44 300 28 20
S34565 115 795 60 415 28 20
S33228 73 500 27 185 28 20

Material Furnished to this specification shall conform to the requirements of specifications A960/A960M including any supplementary requirements that are indicates in the purchase order. Failure to company with the common requirements of Specification A960/A960M constitutes non-conformance with this specification . In case of conflict between this specification and Specification A960/A960M , this specification shall prevail.

Material Furnished to this specification shall conform to the requirements of specifications A960/A960M including any supplementary requirements that are indicates in the purchase order. Failure to company with the common requirements of Specification A960/A960M constitutes non-conformance with this specification. In case of conflict between this specification and Specification A960/A960M , this specification shall prevail.

What grade of steel is ASTM A403?

The standard includes several grades of austenitic stainless steel alloys, and uses the WP or CR prefix to mark the grade of steel, depending on the applicable ASTM or MSS size and rated pressure standards. ASTM A403 is designed for forged steel pipe fittings, Cast pipe fittings are not suitable.

Chemical Composition (%) of ASTM A420

Elements WPL6, % WPL9, % WPL3, % WPL8, %
Carbon [C] ≤0.30 ≤0.20 ≤0.20 ≤0.13
Manganese [Mn] 0.50-1.35 0.40-1.06 0.31-0.64 ≤0.90
Phosphorus [P] ≤0.035 ≤0.030 ≤0.05 ≤0.030
Sulfur [S] ≤0.040 ≤0.030 ≤0.05 ≤0.030
Silicon [Si] 0.15-0.40 0.13-0.37 0.13-0.37
Nickel [Ni] ≤0.40 1.60-2.24 3.2-3.8 8.4-9.6
Chromium [Cr] ≤0.30 ... ... ...
Molybdenum [Mo] ≤0.12 ... ... ...
Copper [Cu] ≤0.40 0.75-1.25
Columbium [Cb] ≤0.02 ... ... ...
Vanadium[V] ≤0.08 ... ... ...

Notes:

*For grade WPL6, the limit for Columbium may be increased up to 0.05% on heat analysis and 0.06% on product analysis.

*Fittings of WPL3 made from plate or forgings may have 0.90 % max manganese.

*Fittings of WPL8 made from plate may have 0.98 % max manganese.

Mechanical properties of ASTM A420

ASTM A420/ A420M Tensile Strength, min. Yield Strength, min. Elongation %, min
Grade ksi MPa ksi MPa Longitudinal Transverse
WPL6 65-95 415-655 35 240 22 12
WPL9 63-88 435-610 46 315 20
WPL3 65-90 450-620 35 240 22 14
WPL8 100-125 690-865 75 515 16

*All the elongation values are on the basis of standard round specimen, or small proportional specimen, min % in 4 D.

ASTM A234 is Standard Specification for steel pipe fittings includes carbon and alloy steel material for moderate and high temperature services.

ASME B16.9 Standard covers overall dimensions, tolerances,ratings, testing, and markings for factory-made wrought buttwelding fittings in sizes NPS 1⁄2 through NPS 48 (DN 15 through DN 1200).

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ASME / ANSI B16.9 dimension

Nominal Outside Diameter 90° Elbows 45° Elbows 180° Returns
Pipe Size
Long Radius Short Radius Long Radius Long Radius
(inches) (mm) (inches) Center to Face Center to Face Center to Face Radius Center to Center Back to face
(inches) (inches) (inches) (inches) (inches) (inches)
1/2 21.3 0.84 1.5 5/8 2 1.875
3/4 26.7 1.05 1.125 7/16 2.25 1.6875
1 33.4 1.315 1.5 1 7/8 3 2.1875
1.25 42.2 1.66 1.875 1.25 1 3.75 2.75
1.5 48.3 1.9 2.25 1.5 1.125 3 4.5 3.25
2 60.3 2.375 3 2 1.375 4 6 4.1875
2.5 73 2.875 3.75 2.5 1.75 5 7.5 5.1875
3 88.9 3.5 4.5 3 2 6 9 6.25
3.5 101.6 4 5.25 3.5 2.25 7 10.5 7.25
4 114.3 4.5 6 4 2.5 8 12 8.25
5 141.3 5.563 7.5 5 3.125 10 15 10.3125
6 168.3 6.625 9 6 3.75 12 18 12.3125
8 219.1 8.625 12 8 5 12 24 16.3125
10 273.1 10.75 15 10 6.25 15 30 20.375
12 323.9 12.75 18 12 7.5 18 36 24.375

Tolerances of Welded Fittings

NOMINAL PIPE SIZE NPS ANGULARITY TOLERANCES ANGULARITY TOLERANCES
Size Off Angle Q Off Plane P
½ to 4 0.03 0.06
5 to 8 0.06 0.12
10 to 12 0.09 0.19
14 to 16 0.09 0.25
18 to 24 0.12 0.38
26 to 30 0.19 0.38
32 to 42 0.19 0.5
44 to 48 0.18 0.75

All dimensions are given in inches. Tolerances are equal plus and minus except as noted.

  1. Out-of-round is the sum of absolute values of plus and minus tolerance.
  2. This tolerance may not apply in localized areas of formed fittings where increased wall thickness is required to meet design requirements of ASME B16.9.
  3. The inside diameter and the nominal wall thicknesses at ends are to be specified by the purchaser.
  4. Unless otherwise specified by the purchaser, these tolerances apply to the nominal inside diameter, which equals the difference between the nominal outside diameter and twice the nominal wall thickness.

The ASME B16.9 pipe fittings can be used under the jurisdiction of the ASME Boiler & Pressure Vessel Code (BPVC) as well as the ASME Code for pressure piping. Referencing pressure ratings of flanges per ASME B16.5, they can be designated as Classes 150, 300, 600, 900, 1500 and 2500. The allowable pressure ratings for ASME B16.9 pipe fittings may be calculated as for straight seamless pipe of equivalent material in accordance with the rules established in the applicable sections of ASME B31 Code for pressure piping.

Design of Fittings

The design of butt welding pipe fittings made to ASME B16.9 shall be established by one of the following methods: (a) mathematical analyses contained in pressure vessel or piping codes; (b) proof testing; (c) experimental stress analysis with hydrostatic testing to validate experimental results; (d) detailed stress analysis with results evaluation.

Standard Marking

Generally, ASME B16.9 pipe fittings shall be marked to show the following details: “trademark + material grade + wall thickness + size + heat number”. For example, “M ASTM A234 WP5 SCH80 6″ 385“. When steel stamps are used, care shall be taken so that
the marking is not deep enough or sharp enough to cause cracks or to reduce the wall thickness of the fitting below the minimum allowed.

Material & Manufacture

The ASME B16.9 fittings may be made from an extensive range of mateirals covering (1) carbon and low-alloy steels in accordance with ASTM A234 and ASTM A420; (2) austenitic and duplex stainless steels in accordance with ASTM A403 and ASTM A815; (3) nickel alloys in accordance with ASTM B366; (4) aluminum alloys in accordance with ASTM B361; and (5) titanium alloys in accordance with ASTM B363.

Pipe Fittings Dimensions Tolerance as per ASME B16.9:

Sizes 1/2″ – 48″

MSS SP-97

MSS SP-97 Standard Practice covers essential dimensions, finish, tolerances, testing, marking, material, and minimum strength requirements for 90 degree integrally reinforced forged branch outlet fittings of buttwelding, socket welding, and threaded types.

Chemical Composition Requirements of MSS SP 75

Elements Value, %
Carbon (C) ≤0.30
Manganese (Mn) ≤1.60
Phosphorus (P) ≤0.035
Sulfur (S) ≤0.035
Copper (Cu) ≤0.50
Nickel (Ni) ≤0.50
Silicon (Si) ≤0.50
Chromium (Cr) ≤0.25
Molybdenum (Mo) ≤0.13
Vanadium (V) ≤0.13
Columbium (Cb) ≤0.10
Titanium(Ti) ≤0.05

*1. The sum of Cu, Ni, Cr and Mo shall not exceed 1%.

*2. Carbon equivalent C.E.=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15 shall not exceed 0.45%.


Benefits

Stub ends are essential components used in various industrial applications, particularly in piping systems.

Stub end benefits

The use of stub ends has these two advantages:

Reduces the overall cost of the flanged joint Generally, the lap joint flange is of a lower grade than the material of the stub end and the pipework, thus saving the total weight of high-grade material used for the flanged joint.

Reduces the overall cost of the flanged joint

Generally, the lap joint flange is of a lower grade than the material of the stub end and the pipework, thus saving the total weight of high-grade material used for the flanged joint.

Example:

For an SS316 pipe, instead of using a full 316 welding neck flange, a combination of an SS316 stub end and a carbon steel lap joint flange would do the same exact job, but the total weight of SS316 material would be lower, and the cost as well.

Essentially, stub ends allow to minimize the weight of high-grade material in stainless, duplex, and nickel alloy piping, saving costs. Of course, the bigger the diameter and the class of the flanges, the higher the saving!

Commercial benefits

Commercial advantages are that the Stub End, will be wetted and it must be made of a grade of material that meets the process design and service conditions of the pipeline. However, the Lap Flange is un-wetted and it can be made of a lower grade of material as long as it meets the mechanical strength requirements of the piping systems.

Installation benefits

The “loose” Flange concept of a Lap Joint, is very beneficial during field installation of piping systems. If two spools are to be mated up in the field, having one Flange that can be rotated is very advantageous when aligning the bolt holes, prior to the introduction of the Stub bolt and the accompanying nuts. The facility of easier orientation and alignment of bolt holes, is of particular use it there is a spool that has to be removed frequently, if positive isolation is a process requirement.

Stub Ends limitations

While stub ends offer numerous advantages in piping systems, it's essential to also consider their limitations. Being aware of these limitations helps engineers, designers, and operators make informed decisions when selecting fittings for specific applications. Let's explore some of the key limitations associated with stub ends:

1. Limited Pressure Ratings:

Stub ends, particularly those used in lap joint flange connections, often have lower pressure ratings compared to fully welded or threaded alternatives. This limitation makes them unsuitable for high-pressure applications.

2. Not Suitable for All Materials:

Stub ends are typically made from materials that can be easily formed and welded, such as stainless steel and carbon steel. However, they may not be compatible with certain materials like exotic alloys or non-metallic materials.

3. Vulnerable to Vibration and Movement:

In applications where there is significant vibration, movement, or mechanical stress, stub ends may not provide the same level of reliability as fully welded connections. The slip-on design could potentially lead to loosening or disconnection.

4. Lack of Full Connection Strength:

Unlike fully welded joints, stub ends rely on the lap joint flange for connection strength. This means the joint's integrity is dependent on the quality of the flange and the fasteners used.

5. Potential for Leakage:

Due to the gapped design between the pipe end and the flange, there is a risk of leakage, especially when dealing with fluids or gases under pressure. The joint might require additional sealing measures to prevent leaks.

6. Incompatible with High-Temperature Applications:

Certain materials used for stub ends may not withstand extremely high temperatures, limiting their application in industries where elevated temperatures are common.

7. Restrictions in Pipe Movement:

Stub ends might limit axial pipe movement and thermal expansion compared to fully flexible joints. This could impact the system's ability to accommodate changes in temperature or pressure.

8. Dependency on Flange Quality:

The effectiveness of stub ends relies on the quality of the lap joint flange and the proper installation of fasteners. Any issues with flange quality or installation can compromise the joint's integrity.

9. Not Ideal for Critical Applications:

For applications where a secure and leak-proof connection is paramount, such as those involving hazardous or toxic substances, fully welded joints may be preferred over stub ends.

10. Maintenance and Inspection Challenges:

Stub ends can be harder to inspect and maintain compared to fully welded joints, as visual assessment of the joint's condition may be limited due to the slip-on design.

11. Limited Applications in High-Corrosion Environments:

Stub ends, particularly those made from certain materials, may not be suitable for use in environments with severe corrosion or aggressive chemical exposure.

In conclusion, while stub ends offer various advantages, they also come with specific limitations that need to be carefully considered during the selection and design of piping systems. Engineers and operators should evaluate the specific requirements of each application and assess whether the benefits of using stub ends outweigh their limitations. By making informed decisions, industries can ensure safe, reliable, and efficient piping networks that meet the demands of their operational environments.

Stub end benefits

Why use Stub Ends?

A stud end and a lap joint flange can be used together as an alternative way to make a flanged connection than welding neck flanges.

Using a stud end and a lap joint flange provides an alternative method for creating a flanged connection, different from welding neck flanges.

The components involved are:

  1. Stub End: This is akin to a pipe segment, with one end flared outward and the other prepped for welding to a pipe of the same bore size (NPS = nominal pipe size), material, and wall thickness. Flaring machines are commonly employed to shape the pipe end and then trim it to the desired length.
  2. Lap Joint Flange: This flange type facilitates bolting the two pipe segments together, creating a secure connection.

This approach offers flexibility and ease of assembly, making it a valuable alternative to traditional welding neck flanges.

Industrial Applications

Stub end is widely used in the petroleum, chemical, power, gas, metallurgy, shipbuilding and construction industries. It is made from high quality raw materials, and available in a variety of sizes and designs.

Stub End usded in Electric power industry

Electric power industry

Stub End used in Petrochemical Industry

Petrochemical Industry

Stub End used in Instrumentation and Electronics

Instrumentation and Electronics

Stub End used in Mechanical Equipment

Mechanical Equipment

Stub End used in Shipbuilding Manufacturing

Shipbuilding Manufacturing

Stub End used in Ocean Engineering

Ocean Engineering

Stub End used in Food & Pharmaceuticals

Food & Pharmaceuticals

Stub End used in Clean Gas

Clean Gas

Stub End used in Papermaking Industry

Papermaking Industry

Stub End used in Vehicle Traffic

Vehicle Traffic

Stub End used in Environmental Management

Environmental Management

Stub End are used in Municipal Engineering

Municipal Engineering

The use of stub ends has these two advantages:

Stub end is widely used in the petroleum, chemical, power, gas, metallurgy, shipbuilding and construction industries. It is made from high quality raw materials, and available in a variety of sizes and designs. The combination of stub ends and backing flanges is an alternative way to join pipes compared to the use of standard flanges.

90° Lateral Wye R500 DN150 Export to Pilipinas with lap-joint flanges

This solution is used in these typical scenarios:

Delivery

Inspection

Visual Inspection is conducted on fittings to check any surface imperfections. Both fittings body and weld are checked for any visible surface imperfections such as dents, die marks, porosity, undercuts, etc. Acceptance as per applicable standard.

ASTM A234 WPB eccentric reducers
ASTM A234 WPB eccentric reducers
ASTM A234 WPB eccentric reducers
ASTM A234 WPB eccentric reducers
ASTM A234 WPB eccentric reducers
ASTM A234 WPB eccentric reducers
ASTM A234 WPB eccentric reducers
ASTM A234 WPB eccentric reducers
ASTM A234 WPB eccentric reducers

Packing

For packing of carbon steel flanges with painting,we would use the bubble wrap to protect the painting.For flanges without painting or oiled with long-term shipment,we would suggest client to use the anti-tarnish paper and plastic bag to prevent the rust.

【H】 Ceramic lined pipe

Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.

【H】 Cast basalt lined steel pipe

Cast basalt lined steel pipe is composed by lined with cast basalt pipe, outside steel pipe and cement mortar filling between the two layers.

【H】 Ceramic Tile Lined Pipes

Ceramic tile lined pipes have very uniform coating of specially formulated ceramic material that is affixed to the inner of the pipe.

【H】 Rare earth alloy wear-resistant pipe

The material of the rare earth alloy wear-resistant pipe is ZG40CrMnMoNiSiRe, which is also the grade of rare earth alloy steel.

【H】 Tubes Erosion Shields

Tubes Erosion Shields are used to protect boiler tubing from the highly erosive effects of high temperatures and pressures thereby greatly extending tube life.

【H】 ASTM A213 T91 Alloy Tube

The ASTM A213 T91 seamless tubes are primarily used for boiler, superheater, and heat-exchanger.

Ni-Hard Wearback Pipes Ni-Hard Wearback Pipes
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