Type A Stainless Steel Stub End

S&S Stainless International manufactures precision-engineered stainless steel Type A stub ends specifically designed to pair with standard ASME B16.5 Lap Joint Flanges. Featuring a carefully machined, radiused outer corner on the lap flare, Type A stub ends allow the backing flange to seat perfectly flush, enabling 360-degree rotation for fast, effortless bolt-hole alignment and lower overall installation costs. Produced in premium 304/304L and 316/316L stainless steel grades to ANSI/ASME B16.9 and MSS SP-43 standards, our seamless and welded Type A stub ends are available in both long and short patterns across complete schedule wall thicknesses, offering superior corrosion resistance and leak-tight joint integrity for chemical processing, oil and gas, power generation, and water treatment systems worldwide.

What is Type A stainless steel stub end?

The Type A stainless steel stub end is a high-quality ASME B16.9 stainless steel pipe fitting designed for use with lap joint flanges, providing an efficient and cost-effective way to connect piping systems. The Type A stainless steel stub end features a flat welding surface and a shorter, thinner hub near the pipe, ensuring easy installation and reliable performance. Type A stainless steel stub ends are commonly used in applications where frequent disassembly is required or in corrosive environments where the flange material can differ from the stub end.

Manufactured to meet international standards such as ASME, ASTM, JIS, and DIN, our Type A stainless steel stub ends deliver precision, durability, and corrosion resistance, making them ideal for industries such as chemical processing, petrochemical, and water treatment.

Product Overview of Type A stainless steel stub end

  • Specification 
    • Material Grade 304, 316, 316L
    • Nominal Pipe Size 1/2” – 24”
    • Thickness SCH 5S, SCH 10S, SCH 40S, SCH 80S
    • Length ANSI, MSS
  • Product Weight
  • Product Packaging

    • Secure Export Packaging: Packed in seaworthy wooden bundles, protective cardboard, or heat-treated wooden cases to prevent transit damage.

    • Accurate & Labeled: Items are carefully sorted, packed, and labeled against the packing list for correct quantities and easy identification.

Product Specification of stainless steel stub end

DN15 – DN600

ASME B16.9 type A stainless stub end dimension chart, sizing from DN15 to 600.
 

Nominal Pipe Size Outside Diameter Thickness(mm) Diameter of Lap (G, mm) Length(F, mm) Radius(R, mm)
DN Inch mm SCH 5S SCH 10S SCH 40S SCH 80S ANSI MSS Type A(Max) Type B(Max)
15 ½’’ 21.3 1.65 2.11 2.77 3.73 34.93 76.2 50.8 3.3 0.76
20 ¾’’ 26.7 1.65 2.11 2.87 3.91 42.88 76.2 50.8 3.3 0.76
25 1’’ 33.4 1.65 2.77 3.38 4.55 50.80 101.6 50.8 3.3 0.76
32 1 ¼’’ 42.2 1.65 2.77 3.56 4.85 63.50 101.6 50.8 4.83 0.76
40 1 ½’’ 48.3 1.65 2.77 3.68 5.08 73.02 101.6 50.8 6.35 0.76
50 2’’ 60.3 1.65 2.77 3.91 5.54 92.07 152.4 63.5 7.78 0.76
65 2 ½’’ 73.0 2.11 3.05 5.16 7.01 104.77 152.4 63.5 7.78 0.76
80 3’’ 88.9 2.11 3.05 5.49 7.62 127.00 152.4 63.5 9.65 0.76
100 4’’ 114.3 2.11 3.05 6.02 8.56 157.18 152.4 76.2 11.18 0.76
125 5’’ 141.3 2.77 3.40 6.55 9.53 185.75 203.2 76.2 11.18 1.52
150 6’’ 168.3 2.77 3.40 7.11 10.97 215.90 203.2 88.9 12.7 1.52
200 8’’ 219.1 2.77 3.76 8.18 12.7 269.88 203.2 101.6 12.7 1.52
250 10’’ 273.1 3.4 4.19 9.27 12.7 323.85 254.0 127.0 12.7 1.52
300 12’’ 323.9 3.96 4.57 9.53 12.7 381.00 254.0 152.4 12.7 1.52
350 14’’ 355.6 3.96 4.78 9.53 12.7 412.75 304.8 152.4 12.7 1.52
400 16’’ 406.4 3.96 4.78 9.53 12.7 469.90 304.8 152.4 12.7 1.52
450 18’’ 457.2 3.96 4.78 9.53 12.7 533.40 304.8 152.4 12.7 1.52
500 20’’ 508 4.78 5.54 9.53 12.7 584.20 304.8 152.4 12.7 1.52
550 22’’ 558.8 4.78 5.54 9.53 12.7 641.35 304.8 – 12.7 1.52
600 24’’ 609.6 5.54 6.35 9.53 12.7 692.15 304.8 152.4 12.7 1.52

FAQs

1. What is the structural feature of a Type A stub end, and why must it be used with a Lap Joint Flange?

A Type A stub end features a specifically radiused outer corner on the inside lap flare. This radius is engineered to match the female inside bore radius of a standard ASME B16.5 Lap Joint Flange. The matching radii allow the loose backing flange to seat completely flush against the back of the lap, ensuring uniform pressure distribution across the gasket face and preventing structural binding.

We manufacture Type A stub ends via seamless pipe flanging or hot forging to ensure maximum material integrity without seam welds in the flare zone. For larger pipe sizes, welded options formed from plate are available. The lap face can be supplied with a smooth machined finish or serrated concentric/spiral grooves per ASME B16.9 to optimize gasket sealing under high operating pressures.

Quality control includes 100% Positive Material Identification (PMI) chemical verification and full solution heat treatment (annealing) to eliminate work hardening in the formed lap area. QC inspectors measure the lap radius, lap face thickness, and pipe wall thickness using precision gauges and ultrasonic meters to guarantee strict compliance with ASME B16.9 or MSS SP-43 tolerances. Full EN 10204 3.1 Material Test Reports (MTRs) accompany every shipment.

Standard factory production lead time is 30 to 45 days upon order confirmation and technical drawing approval. We maintain flexible MOQs for standard sizes in dual-certified 304/304L and 316/316L material grades (in both long and short patterns), allowing international procurement teams to mix stub ends with lap joint flanges, elbows, tees, and reducers in a single consolidated container shipment.

Because the machined sealing face is critical to joint integrity, all lap faces are treated with rust-inhibiting oil, fitted with plastic protective face covers, and separated by cardboard dividers. Stub ends are packed inside ISPM-15 heat-treated, seaworthy wooden cases lined with waterproof plastic film. For large-diameter orders, items are securely strapped to wooden pallets with protective corner cushioning to prevent metal-to-metal impact during ocean transit.

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