Buttweld Lap Joint Stub End
Lap Joint Stub End : Specifications | Materials | Types | Dimensions | Weight Chart | Tolerances | FAQ
Leading ASME B16.9 Buttweld Lap Joint Stub End Manufacturer & Exporter – Supplying Premium Lap Joint Stub Ends in Stainless Steel, Carbon Steel, Alloy Steel, and High Nickel Alloys (Seamless & Welded, SCH 40 / SCH 80) to Germany, Australia, South Africa, UAE, and the USA.
Best Export Prices: sales@midlandforgefittings.com
Midland Forge and Fittings Pvt. Ltd. is a leading provider of ASME B16.9 Lap Joint Stub Ends, engineered for demanding industrial applications. Precision-manufactured and quality-tested, our stub ends are fully compatible with lap joint flanges and ideal for systems requiring frequent dismantling and inspection. They offer seamless integration, corrosion resistance, and long-term reliability across petrochemical, food processing, and marine industries.
Serving clients in countries including Germany, Australia, South Africa, UAE, and the USA, Midland combines in-house manufacturing, flexible customization, and timely delivery. Trusted in large-scale EPC projects and fast-paced industrial environments, our stub ends deliver consistent quality backed by global certifications.
Lap Joint Stub Ends are used with lap joint flanges in systems that require frequent dismantling. Ideal for low- and high-pressure pipelines, they allow easy flange alignment and reduce weld stress. Available in short and long patterns, they are manufactured as per ASME B16.9 in Seamless (½″ NB to 24″ NB) and Welded (up to 48″ NB) forms. Common materials include Stainless Steel, Carbon Steel, Alloy Steel, and High Nickel Alloys, making them suitable for corrosive and high-temperature applications.
Lap Joint Stub End Specifications, Sizes & Standards
Buttweld Lap Joint Stub End – Materials, Grades & Standards
| Material Category | Grade | Standards (ASTM / ASME) | Typical Use/Application |
|---|---|---|---|
| Stainless Steel | 304 / 304L / 304H | ASTM A403 WP304/304L/304H | General purpose, corrosion resistance |
| 316 / 316L / 316H | ASTM A403 WP316/316L/316H | Marine & chemical applications | |
| 317 / 317L | ASTM A403 WP317/317L | High corrosion resistance | |
| 321 / 321H | ASTM A403 WP321/321H | High temperature, stabilized | |
| 347 / 347H | ASTM A403 WP347/347H | High-temp pressure systems | |
| 904L | ASTM A403 WP904L / B625 | Acid handling, sulfuric environments | |
| 254 SMO | ASTM A403 / B366 | High chloride environments | |
| Carbon Steel | A234 WPB / WPC | ASTM A234 | Pressure piping & general piping systems |
| A420 WPL6 | ASTM A420 | Low temperature services | |
| Alloy Steel | A234 WP1 / WP5 / WP9 | ASTM A234 | High-temp & pressure pipelines |
| A234 WP11 / WP22 | ASTM A234 | Steam lines & refineries | |
| A234 WP91 | ASTM A234 | Power generation, high performance | |
| Duplex Steel | UNS S31803 / S32205 | ASTM A815 / A790 | Corrosion & high strength use |
| Super Duplex Steel | UNS S32750 / S32760 | ASTM A815 / A790 | Offshore, seawater applications |
| Nickel Alloys | Nickel 200 / 201 | ASTM B366 / B162 | Alkali & chemical processing |
| Inconel 600 / 625 / 718 | ASTM B366 | Heat exchangers, aerospace | |
| Incoloy 800 / 825 | ASTM B366 | Petrochemical & chemical processing | |
| Hastelloy C22 / C276 | ASTM B366 | Severe corrosion resistance | |
| Monel 400 / K500 | ASTM B366 | Seawater, chemical industries | |
| Alloy 20 | ASTM B366 | Sulfuric acid services | |
| Nimonic 75 / 80A | ASTM B366 / B637 | High-temp applications | |
| Copper Nickel | Cu-Ni 90/10 / 70/30 | ASTM B466 / B467 | Marine systems, seawater service |
| Titanium | Grade 2 / Grade 5 | ASTM B363 | Lightweight, corrosion resistance |
| Aluminium | 6061 / 5083 | ASTM B361 | Low-pressure, non-corrosive piping |
Dimensions of Lap Joint Stub End
| Nominal Pipe Size (NPS) | OD (mm) | Short Pattern A | Short Pattern B | Short Pattern C | Long Pattern A | Long Pattern B | Long Pattern C | G (mm) | T (mm) |
|---|---|---|---|---|---|---|---|---|---|
| Short Pattern | Long Pattern | G (mm) | T (mm) | ||||||
| 1/2″ | 21.3 | 25 | 38 | 1.6 | 51 | 50 | 1.6 | 34.8 | 2.77 |
| 3/4″ | 26.7 | 32 | 38 | 1.6 | 56 | 50 | 1.6 | 3.55 | 3.56 |
| 1″ | 32.2 | 32 | 18 | 1.6 | 72 | 64 | 1.6 | 3.56 | 3.55 |
| 1 1/2″ | 46.4 | 34 | 16 | 1.6 | 81 | 57 | 1.6 | 5.55 | 3.55 |
| 2″ | 86.9 | 64 | 38 | 1.6 | 195 | 86 | 1.6 | 6.02 | 9.49 |
| 3″ | 88.9 | 64 | 52 | 1.6 | 127 | 102 | 1.6 | 5.85 | 5.55 |
| 4″ | 114.3 | 64 | 57 | 1.6 | 157 | 150 | 1.6 | 7.15 | 6.55 |
| 6″ (1st row) | 273.0 | 64 | 108 | 1.6 | 229 | 169 | 1.6 | 6.27 | 7.11 |
| 6″ (2nd row) | 273.0 | 105 | 153 | 1.6 | 229 | 229 | 1.6 | 9.27 | 9.22 |
| 10″ | 273.9 | 156 | 223 | 1.6 | 229 | 229 | 1.6 | 9.33 | 9.52 |
Weight Chart: ASME B16.9 Lap Joint Stub End (SCH 40 / STD)
| Nominal Pipe Size (NPS) | Short Pattern (kg) | Long Pattern (kg) |
|---|---|---|
| 1/2″ | 0.15 | 0.30 |
| 3/4″ | 0.25 | 0.45 |
| 1″ | 0.35 | 0.60 |
| 1 1/4″ | 0.50 | 0.90 |
| 1 1/2″ | 0.60 | 1.10 |
| 2″ | 0.90 | 1.65 |
| 2 1/2″ | 1.20 | 2.00 |
| 3″ | 1.50 | 2.40 |
| 4″ | 2.20 | 3.60 |
| 5″ | 2.80 | 4.80 |
| 6″ | 3.60 | 6.50 |
| 8″ | 5.60 | 10.00 |
| 10″ | 7.80 | 14.50 |
| 12″ | 10.50 | 19.00 |
| 14″ | 13.00 | 24.50 |
| 16″ | 16.00 | 30.00 |
| 18″ | 19.00 | 36.00 |
| 20″ | 23.00 | 43.00 |
| 24″ | 30.00 | 56.00 |
Lap Joint Stub End Fitting Tolerances as per ASME B16.9
| Fitting Type | Parameter | Tolerance | |
|---|---|---|---|
| Up to 4” NPS | Above 4” NPS | ||
| Lap Joint Stub End | Outside Diameter at Bevel | ±1.6 mm (1/16″) | ±1.6 mm (1/16″) |
| Center-to-End (A, B) | ±1.6 mm (1/16″) | ±3.2 mm (1/8″) | |
| Wall Thickness | -12.5% (no positive tolerance) | ||
| Ovality | Shall not exceed 1% of specified OD | ||
What’s the difference between a lap joint stub end and a regular pipe fitting?
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Connection Type: A lap joint stub end is used with a loose backing flange, allowing the flange to rotate freely around the pipe for easy alignment of bolt holes. In contrast, a regular butt-weld fitting is permanently welded to the pipe and does not allow flange rotation.
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Flexibility: Lap joint stub ends are ideal for systems where frequent dismantling, maintenance, or realignment is required, whereas standard fittings are fixed and more permanent.
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Installation in Tight Spaces: The ability to rotate the flange makes stub ends easier to install in tight or misaligned piping systems.
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Pressure Applications: Both can handle pressure, but stub ends are often used in low- to medium-pressure applications where flange alignment is a challenge.
Are lap joint stub ends compatible with all flange types?
No, lap joint stub ends are not compatible with all flange types. They are specifically designed to work with lap joint flanges, which are sometimes also called loose flanges. Here’s why:
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Design Compatibility:
- A lap joint stub end has a short, beveled end that is butt-welded to the pipe.
- The lap joint flange slides over the stub end and rests on its back face, allowing the flange to rotate freely.
- This rotation feature is essential for aligning bolt holes, especially in systems with multiple flanges or in tight spaces.
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Limited to Certain Applications:
- Other flange types such as weld neck, slip-on, socket weld, or blind flanges are designed to be permanently welded or bolted directly to the pipe.
- These flanges do not accommodate the loose sliding feature of a lap joint, so pairing them with a stub end would not work.
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Advantages of Compatibility:
- Using the proper lap joint flange with a stub end ensures easy installation, alignment, and maintenance.
- It also allows frequent dismantling or repositioning of the pipeline without cutting or rewelding, making it ideal for systems where modifications or inspections are common.
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Industry Use:
- Lap joint stub ends with compatible flanges are commonly used in low- to medium-pressure piping systems, chemical plants, water treatment plants, and other industries requiring flexibility and alignment during installation.
How to select the correct lap joint stub end?
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Pipe Size:
- Choose a stub end that matches the nominal pipe size (NPS) and schedule (wall thickness) to ensure proper fit and welding compatibility.
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Pressure Rating:
- Verify that the stub end is rated for the system’s operating pressure. Pressure classes are usually aligned with the corresponding flange rating.
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Material Compatibility:
- Ensure the stub end material is compatible with the pipe and the flange material to avoid corrosion or galvanic reactions. Common materials include carbon steel, stainless steel, and alloy steel.
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Pattern Type (Short vs Long):
- Short pattern stub ends are used for compact piping systems with limited space.
- Long pattern stub ends are used where alignment flexibility and bolt clearance are needed.
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Standards Compliance:
- Always refer to ASME B16.9 dimensions and specifications to ensure the stub end meets industry standards.