Stub End

Stub End

High-performance Stub Ends For Corrosion-resistant Lap Joint Connections In Industrial Piping

A stub end is a pipe fitting designed to be welded to a pipe or lap joint flange, providing a secure and leak-proof connection that allows for easy disassembly.

Easy Maintenance

Allows for quick disassembly without disturbing the entire system, facilitating maintenance and inspection.

Leak-Proof Design

When properly welded and assembled, provides a secure and leak-proof joint for reliable operation.

Cost-Effective

Reduces overall cost by using expensive materials only where needed, with cheaper backing flanges.

What is a Stub End?

A stub end is a type of pipe fitting used in various industrial applications to connect pipes or flanges. It acts as a sleeve that slips over the pipe or lap joint flange, allowing for easy and quick disassembly when needed.

Stub End is a pipe fitting used in industrial piping systems, welded to a pipe and paired with a lap joint flange to form a flanged connection. Compliant with ASTM A234 WPB standards, this carbon steel fitting offers robust pipeline corrosion protection and durability, making it ideal for boiler pipeline protection in oil and gas, petrochemical, and power generation industries as of 2:15 AM PDT, September 01, 2025. Its butt-weld design ensures strong, leak-proof connections, while the lap joint flange facilitates easy alignment and disassembly.

The Stub End is manufactured in three types (A, B, C) and two standard lengths (short and long pattern) using seamless or welded processes. Common materials include ASTM A234 WPB (carbon steel) for general-purpose applications, ASTM A234 WP22 (low-alloy steel) for high-temperature environments, or ASTM A403 TP347H (stainless steel) for superior corrosion resistance. Available in sizes from 1/2” to 48” (DN 15–DN 1200) and wall thicknesses such as SCH 10, SCH 40, or SCH 80, it meets diverse industrial piping requirements. Rigorous testing, including tensile, hydrostatic, and non-destructive tests (radiography or ultrasonic), ensures compliance with ASME B16.9 and MSS SP-43 standards.

Engineered for pipeline corrosion protection, the Stub End can be coated with epoxy, galvanizing, or 3LPE to withstand harsh environments like offshore pipelines or chemical plants. Its robust construction resists wear from abrasive materials and high-pressure conditions, ensuring reliability for boiler pipeline protection. The fitting is welded to the pipe using methods like SMAW, GTAW, or GMAW with compatible fillers (e.g., low-carbon for WPB, E9018-B3 for WP22), ensuring seamless integration with pipelines like ASTM A106 Gr.B or API 5L Gr.B.

Unlike branching fittings like Equal Tee, Reducing Tee, Lateral Tee, or ASTM A234 WP22 Tee (as discussed in your previous queries), the Stub End is designed for flanged connections, enabling cost savings by using lower-grade lap joint flanges (e.g., carbon steel) with high-grade stub ends (e.g., stainless steel). Type A stub ends match lap joint flange profiles, Type B suits slip-on flanges, and Type C is flared for versatility. Its design supports applications requiring frequent disassembly, such as maintenance-heavy systems. For highly corrosive environments, stainless steel options like ASTM A403 TP347H are preferred.

The Stub End addresses challenges like pipeline corrosion, connection reliability, and cost efficiency in industrial systems. Its flexible design and material options ensure long-term performance, safety, and cost-effectiveness, making it a top choice for engineers seeking robust industrial piping and boiler pipeline protection solutions.

Stainless stub end

Key Benefits

Easy Disassembly

Quick removal of piping sections without disturbing the entire system for maintenance and inspection.

Cost-Effective

Use expensive materials only where needed, with cheaper backing flanges reducing overall cost.

Flexibility in Alignment

Rotating backing flange allows easy alignment of bolt holes during installation.

Leak-Proof Connection

Properly welded and assembled stub ends provide secure and leak-proof joints.

Versatility

Compatible with various flange types and available in wide range of materials and sizes.

Quality Assurance

Manufactured to strict international standards with comprehensive testing and inspection.

Types of Stub Ends

By Design & Application

Type "A" Stub End

Description: Produced and machined specifically to fit lap joint flanges.

  • Matching profile surfaces
  • Radius outside corner
  • Squared inside corner
  • For lap joint flanges
Type "B" Stub End

Description: Suited for standard slip-on flanges acting as lap-joint flanges.

  • Serrated lap face
  • Tight joint sealing
  • ID side chamfers required
  • For slip-on flanges
Type "C" Stub End

Description: Versatile for both lap joint and slip-on backing flanges.

  • Flared lap design
  • 75% pipe wall thickness
  • Short fillet outer radius
  • Fabricated from pipes
Type "CS" Stub End

Description: Similar to Type "C" with concentric serrations on lap face.

  • Concentric serrations
  • Enhanced sealing capability
  • Machined during manufacturing
  • Critical sealing applications

By Length Pattern

Long Pattern

Longer length for easier alignment and welding. Suitable for frequent disassembly applications.

Standard Lap Joint Flanges
Short Pattern

Similar length to pipe. Ideal for space-limited applications where flange needs to be close to pipe end.

Slip-On Flanges

Stu end geometry

In piping systems, a stub end is a crucial component used for connecting pipes of different materials and sizes. It provides a convenient and cost-effective solution for achieving a leak-free joint without the need for welding. In this article, we will explore the geometry, types, and applications of stub ends, shedding light on their significance in various industries and projects.

Pipe Fitting Dimensions
N.D. Out diameter Hight(F) Stub end O.D.(G) Beveld radio(R)
NPS DN OD Mss ANSI Nominal&max Nominal&min A Max B Max
1/2 15 21.3 50.8 76.2 35 34 3 0.8
3/4 20 26.7 50.8 76.2 43 42 3 0.8
1 25 33.4 50.8 101.6 51 50 3 0.8
1 1/4 32 42.4 50.8 101.6 64 63 4.8 0.8
1 1/2 40 48.3 50.8 101.6 73 72 6.4 0.8
2 50 60.3 63.5 152.4 92 91 7.9 0.8
2 1/2 65 73 63.5 152.4 105 104 7.9 0.8
3 80 88.9 63.5 152.4 127 126 9.6 0.8
3 1/2 90 101.6 76.2 152.4 140 139 9.6 0.8
4 100 114.3 76.2 152.4 157 156 11.2 0.8
5 125 141.3 76.2 203.2 186 185 11.2 1.6
6 150 168.3 88.9 203.2 216 215 12.7 1.6
8 200 219.1 101.6 203.2 270 269 12.7 1.6
10 250 273.1 127 254 324 322 12.7 1.6
12 300 323.9 152.4 254 381 379 12.7 1.6
14 350 355.6 152.4 304.8 413 411 12.7 1.6
16 400 406.4 152.4 304.8 470 468 12.7 1.6
18 450 457.2 152.4 304.8 533 531 12.7 1.6
20 500 508 152.4 304.8 584 582 12.7 1.6
22 550 559 152.4 304.8 641 639 12.7 1.6
24 600 610 152.4 304.8 692 690 12.7 1.6

How to order a Stub Ends

The following information shall be provided to order a stub end:

  • NPS
  • Schedule
  • Length (according to norms MSS SP43 / ASME B16.9 / custom)
  • Specs and material grade
  • Ends finish
  • Execution: seamless / welded (wx)

Stub end finish

Stub ends can be ordered with different ends finishing:

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

Materials & Standards

Material Type Standards & Grades Characteristics Applications
Carbon Steel ASTM A234 WPB, A420 WPL6 High strength, cost-effective, good weldability General industrial piping, oil & gas, power generation
Stainless Steel ASTM A403 WP304/304L, WP316/316L Excellent corrosion resistance, hygienic properties Chemical processing, food & beverage, pharmaceutical
Alloy Steel ASTM A234 WP1, WP5, WP9, WP11, WP22, WP91 Enhanced strength, high-temperature resistance High-temperature and high-pressure services

Manufacturing Standards

ASME B16.9

Butt Weld Fittings

MSS SP-43

Stainless Steel Fittings

ASME B16.25

Buttwelding Ends

JIS B2312/B2313

Japanese Standards

Delivery

Stub End Applications

The Stub End allows sections pipe to be opened for inspection, cleaning or replacement without the need for additional welding.

  • Petroleum
  • Chemical
  • Power
  • Oil & Gas
  • Metallurgy
  • Shipbuilding
  • Construction industries

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