ASTM A135 ERW Pipe
Basic Overview
ASTM A135 (identical to ASME SA-135) is the standard specification for electric-resistance-welded (ERW) steel pipe intended for conveying gas, vapor, water, or other liquids [citation:4, citation:6]. It covers two grades of ERW pipe and is commonly used for low-pressure plumbing, fire protection systems, and general-purpose water lines .
This specification is specifically designed for ERW pipe only-unlike ASTM A53 which covers multiple manufacturing methods, A135 is exclusively for electric-resistance-welded pipe [citation:1, citation:4].
Name Explanation
| Part | Meaning |
|---|---|
| ASTM | ASTM International (American Society for Testing and Materials) |
| A135 | Standard specification for electric-resistance-welded steel pipe |
| ERW | Electric Resistance Welded – pipe formed from steel coil and welded longitudinally without filler metal [citation:4, citation:6] |
Key Features
| Feature | Description |
|---|---|
| Manufacturing | Electric Resistance Welded (ERW) only – high-frequency welding process [citation:4, citation:6] |
| Grades | Grade A and Grade B [citation:4, citation:8] |
| Size Range | NPS 2 to NPS 30 (DN 50 to DN 750) with wall thickness up to 0.500″ (12.7 mm); also NPS ¾ to 5 with lighter walls [citation:4, citation:6] |
| Wall Thickness | Common schedules: SCH 10, SCH 40 [citation:1, citation:9] |
| Finish Options | Black (bare), red epoxy, or galvanized; often red-coated for fire protection |
| Special Feature | Only Grade A is adapted for flanging and bending [citation:4, citation:6] |
Chemical Composition
| Element | Grade A (max %) | Grade B (max %) |
|---|---|---|
| Carbon (C) | 0.25 | 0.30 [citation:4, citation:6, citation:10] |
| Manganese (Mn) | 0.95 | 1.20 [citation:4, citation:6, citation:10] |
| Phosphorus (P) | 0.035 | 0.035 [citation:4, citation:6, citation:10] |
| Sulfur (S) | 0.035 | 0.035 [citation:4, citation:6, citation:10] |
Mechanical Properties
| Property | Grade A | Grade B |
|---|---|---|
| Yield Strength (min) | 205 MPa (30,000 psi) | 240 MPa (35,000 psi) [citation:4, citation:6, citation:8, citation:10] |
| Tensile Strength (min) | 330 MPa (48,000 psi) | 415 MPa (60,000 psi) [citation:4, citation:6, citation:8, citation:10] |
| Elongation (min) | 35% | 30% [citation:4, citation:6, citation:10] |
Dimensional Specifications
| Parameter | Range |
|---|---|
| Outside Diameter | NPS 2 to 30 (approx. 60.3 mm to 762 mm) [citation:4, citation:6] |
| Wall Thickness | Up to 0.500″ (12.7 mm) for NPS 2-30; 0.083″ to 0.134″ for NPS ¾-5 [citation:4, citation:6] |
| Length | Typically 6 m, 9 m, 12 m, or 18 m |
| End Finishes | Plain ends, beveled ends, threaded ends, or roll grooved [citation:4, citation:9] |
| Cold Expansion | If expanded, shall not exceed 1.5% of outside diameter [citation:4, citation:6] |
Grade A vs. Grade B Comparison
| Property | Grade A | Grade B |
|---|---|---|
| Yield Strength | 205 MPa (30 ksi) | 240 MPa (35 ksi) |
| Tensile Strength | 330 MPa (48 ksi) | 415 MPa (60 ksi) |
| Carbon Content | ≤ 0.25% | ≤ 0.30% |
| Formability | Adapted for flanging and bending [citation:4, citation:6] | Not recommended for severe forming |
| Typical Use | Light fabrication, bending applications | Higher pressure, general service |
Heat Treatment Requirements
The weld seam of Grade B pipe must be heat treated after welding to a minimum temperature of 1000°F (540°C) or processed to ensure no untempered martensite remains [citation:4, citation:6, citation:10]. This heat treatment:
Temps the martensite at the weld for improved stability
Enhances overall pipe performance
Prevents brittle failure at the weld seam
Testing Requirements
| Test Type | Requirement |
|---|---|
| Chemical Analysis | Per heat lot [citation:4, citation:6] |
| Tension Test | Per lot [citation:4, citation:6] |
| Hydrostatic Test | Each pipe NPS 2 and larger; nondestructive testing permitted as alternative [citation:1, citation:4] |
| Flattening Test | As required [citation:4, citation:6] |
| Nondestructive Electric Test | When specified by purchaser [citation:4, citation:6] |
| Dimensional Inspection | 100% [citation:4, citation:6] |
Common Applications
| Application | Description |
|---|---|
| Fire Protection Systems | Wet, dry, preaction, and deluge sprinkler systems [citation:1, citation:9]; often UL/FM certified |
| Water Distribution | Low-pressure water lines, general plumbing |
| Gas and Vapor | Conveying gas and vapor [citation:4, citation:6] |
| Low-Pressure Fluid Transmission | General liquid service [citation:4, citation:5] |
Key Differences: ASTM A135 vs. ASTM A53
| Aspect | ASTM A135 | ASTM A53 |
|---|---|---|
| Manufacturing | ERW only | ERW, seamless, and furnace welded [citation:2, citation:8] |
| Size Range | NPS 2 to 30 [citation:4, citation:6] | NPS 1/8 to 26 |
| Grades | A, B [citation:4, citation:8] | A, B (C for seamless) |
| Special Feature | Only Grade A for flanging/bending [citation:4, citation:6] | Grade A and B both available |
| Primary Market | Fire protection, low-pressure fluid | General utility, structural, pressure |
Important Considerations
1. Grade Selection
Grade A: Choose when the pipe requires flanging, bending, or close coiling [citation:4, citation:6]
Grade B: Choose for higher strength requirements where forming is not required
2. Size Limitations
A135 is primarily specified for NPS 2 and larger
For smaller diameters (NPS ½ to 1½), other specifications like A53 or A795 may be more appropriate
3. Fire Protection Market
A135 is a key specification for fire sprinkler systems
Often combined with UL/FM certification for building code compliance
Common coatings: red epoxy or red paint for identification
4. Wall Thickness
For fire protection, SCH 10 and SCH 40 are standard [citation:1, citation:9]
SCH 10 pipe is typically furnished plain end only [citation:4, citation:6]
5. End Preparation Options
Plain ends (standard)
Beveled ends (for welding)
Threaded ends (with coupling provided)
Roll grooved (for mechanical couplings) [citation:1, citation:9]
Summary
ASTM A135 ERW pipe is the standard specification for electric-resistance-welded steel pipe used in low-pressure fluid transmission, fire protection systems, and general utility applications [citation:5, citation:6].
Key features:
Manufactured only by ERW process – no seamless or other weld types
Two grades – Grade A (205 MPa yield, formable) and Grade B (240 MPa yield, higher strength)
Size range – NPS 2 to 30 (up to 30″ diameter)
Special forming note – Only Grade A is suitable for flanging and bending [citation:4, citation:6]
Heat treatment – Grade B weld seam requires treatment at 1000°F minimum [citation:4, citation:10]
Commonly used for:
Fire sprinkler systems (often with UL/FM certification) [citation:1, citation:9]
Water distribution and low-pressure plumbing
Gas and vapor lines
When ordering, specify: quantity, product name, wall thickness, standard specification, grade, size, unit length, and end finish . For example: *ASTM A135 Gr.B ERW pipe, 6″ SCH40, L=6m, plain ends* .
