ASTM A53 Type F: Longitudinally Submerged Arc Welded Pipe
ASTM A53 is a standard specification for pipe, steel, black and hot-dipped, zinc-coated, welded and seamless. It covers both seamless and welded steel pipe, with the welded types further classified by their manufacturing process.
Type F specifically denotes pipe that is furnace-butt welded (a continuous weld process). However, the most common longitudinal welded type under ASTM A53 that uses the Submerged Arc Welding (SAW) process is often associated with the Electric Resistance Welded (ERW) or Fusion Welded categories, but with a supplementary requirement for the weld seam to be processed via SAW. It's important to note that the standard primary welded type is ERW.
For clarity, a longitudinally Submerged Arc Welded (SAW) pipe with similar characteristics to A53 but typically made from plate/coil is often specified under ASTM A139. If a pipe is explicitly described as "ASTM A53 Longitudinally Submerged Arc Welding," it typically means it is produced to meet the chemical, mechanical, and testing requirements of ASTM A53, but using a SAW longitudinal weld method, which may be considered under special provisions or as a "grade" within custom manufacturing.
The following information details the properties of such a pipe, assuming it conforms to the core requirements of ASTM A53 for welded pipe.
Key Characteristics of Longitudinally SAW Pipe to ASTM A53
Manufacturing Process: A steel plate or coil is formed into a cylindrical shape. The longitudinal seam is then welded on the inside and outside using the Submerged Arc Welding (SAW) process. In SAW, the arc is buried under a layer of fusible granular flux, resulting in a high-quality, deep-penetration weld with excellent mechanical properties and a smooth appearance.
Common Applications: This pipe is widely used in low-pressure structural applications, piling, conveyor rollers, and other mechanical applications. It is not intended for high-temperature or high-pressure fluid service (where ASTM A106 or API 5L would be more common). For critical applications, Grade B is typically specified.
Available Conditions: As-welded (no subsequent heat treatment) or cold-expanded (which improves dimensional accuracy and relieves some stresses).
Sizes: Typically available in larger diameters and thicker walls compared to standard ERW pipe. Common NPS (Nominal Pipe Size) ranges from about 10 inches (250 mm) and above, with walls suitable for structural demands.
Technical Specification Tables
Table 1: Grades and Mechanical Properties
| Grade | Tensile Strength, min (psi / MPa) | Yield Strength, min (psi / MPa) | Elongation in 2 in. (50 mm), min % |
|---|---|---|---|
| A | 48,000 / 330 | 30,000 / 205 | See Table 2 |
| B | 60,000 / 415 | 35,000 / 240 | See Table 2 |
Note: Elongation requirements vary with wall thickness and are specified in the standard.
Table 2: Chemical Composition (Heat Analysis, Maximum % unless noted)
| Grade | Carbon (C) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) | Copper (Cu) min* | Nickel (Ni) min* | Chromium (Cr) min* | Molybdenum (Mo) min* |
|---|---|---|---|---|---|---|---|---|
| A | 0.25 | 0.95 | 0.05 | 0.045 | 0.40 | 0.40 | 0.40 | 0.15 |
| B | 0.30 | 1.20 | 0.05 | 0.045 | 0.40 | 0.40 | 0.40 | 0.15 |
* These four elements (Cu, Ni, Cr, Mo) have a minimum requirement only when the specified minimum copper content is agreed upon between purchaser and manufacturer.
Table 3: Common Testing Requirements
| Test Name | Description | Frequency / Requirement |
|---|---|---|
| Flattening Test | A section of pipe is flattened between two parallel plates to a specified distance without crack or flaw opening. | Required for all welded pipe. Demonstrates ductility of the weld and parent metal. |
| Hydrostatic Test | Pipe is filled with water and pressurized to a specified minimum pressure for at least 5 seconds. | Required for ALL pipes (seamless and welded) unless replaced by a non-destructive electric test. |
| Non-Destructive Test | Usually an ultrasonic inspection or eddy current test of the entire weld seam. | May be specified as an alternative to the hydrostatic test. Common for SAW pipes. |
| Bend Test | A transverse bend test specimen from the weld area is bent to demonstrate soundness of the weld. | Required if the pipe is not cold-expanded. |
Important Notes & Distinctions
ASTM A53 vs. API 5L: API 5L is the dominant specification for line pipe used in oil and gas transmission. While chemical and mechanical properties can be similar, API 5L has more stringent requirements on weld testing, traceability, and impact toughness for certain grades. SAW line pipe is almost always specified under API 5L.
ASTM A53 vs. ASTM A139: ASTM A139 is the standard specifically for Electric-Fusion (Arc)-Welded Steel Pipe, which explicitly covers SAW pipe. If the primary design and procurement basis is the longitudinal SAW process, ASTM A139 is the more directly applicable standard.
Marking: Pipe marked as "A53 Gr B SAW" would indicate it meets the material requirements of ASTM A53 Grade B, with a longitudinally Submerged Arc Welded seam. The marking would also include the manufacturer's name, size, heat number, and pressure test identifier.
In summary, while "ASTM A53 Longitudinally Submerged Arc Welded Pipe" is a valid description, it often represents a product built to the core material specs of A53 using a high-quality SAW process. For pure SAW fabrication, ASTM A139 is the more precise reference standard.
