top of page

SS Pipes & Fittings

Stainless Steel (SS) Seamless Pipe Fittings

SS SEAMLESS FITTINGS_edited.png

Stainless Steel (SS) Seamless Pipe Fittings are high-integrity components manufactured from solid stainless steel bars or seamless pipes. Because they are forged or extruded without a weld seam, they provide maximum strength, uniform wall thickness, and zero risk of weld-related corrosion or failure, making them the standard for high-pressure, high-temperature, and sanitary applications.

1. Primary Technical Standards

  • Material Standard: ASTM A403 (Standard Specification for Wrought Austenitic Stainless Steel Piping Fittings).

  • Dimensional Standard: ASME B16.9 (Factory-Made Wrought Buttwelding Fittings) or MSS SP-43 (Light Weight Corrosion Resistant Fittings).

  • Marking: Seamless fittings are often marked with the suffix "-S" (e.g., WP304-S) to distinguish them from welded variants.

2. Common Material Grades

The choice of grade depends on the chemical environment of your project:

Grade
Prefix (WP)
Key Characteristic
Common Application
SS 304
WP304
Standard 18% Cr, 8% Ni
General food/industrial use
SS 304L
WP304L
carbon (prevents sensitization)
Heavy welding applications
SS 316
WP316
2-3% Molybdenum added
Marine & Chemical (Chloride resistance
SS 316L
WP316L
Low carbon + Molybdenum
Pharmaceutical & Petrochemical
SS 321
WP321
Titanium stabilized
High heat (Exhausts/Furnaces)

3. Dimensional Data (ASME B16.9 - Seamless)

Seamless fittings match the Schedule (thickness) of the pipe they are connected to.

Nominal Size (NB)
Outer Dia (mm)
Sch 10S Wall (mm)
Sch 40S Wall (mm)
90° Elbow (Center to End)
1/2" (15mm)
21.3
2.11
2.77
38 mm
1" (25mm)
33.4
2.77
3.38
38 mm
2" (50mm)
60.3
2.77
3.91
76 mm
4" (100mm)
114.3
3.05
6.02
152 mm
6" (150mm)
168.3
3.40
7.11
229 mm

4. Technical Properties & Testing

Seamless fittings must undergo rigorous quality checks:

  • Mechanical Strength: Tensile strength of $\geq 515$ MPa and Yield strength of $\geq 205$ MPa (for 304/316).

     

  • Hydrostatic Test: Verified to withstand internal pressure without leakage (often tested at 1.5x the working pressure).

  • Non-Destructive Testing (NDT): Ultrasonic (UT) or Magnetic Particle testing is performed to ensure no internal voids or cracks exist in the forged body.

  • IGC Test: Intergranular Corrosion test (ASTM A262 Practice A or E) to ensure the steel remains corrosion-resistant after the forging process.

5. Surface Finish Options

For suppliers like Asma Enterprises, the finish is critical for specific industries:

  • Annealed & Pickled (AP): Standard industrial finish.

  • Sand Blasted: A matte, clean finish for structural use.

  • Polished (Mirror/Satin): Essential for dairy, food processing, and pharmaceutical lines (Grit 180, 240, or 320).

bottom of page