1. What are the standard specifications or grades for Cold Drawn Pipe?
Answer: Common standards include ASTM A513 for mechanical tubing and ASTM A519 for structural tubing. Specific grades depend on the material (e.g., 1018, 1020, 1026, 4130 for carbon steels; 304, 316 for stainless steels). These standards define the chemical composition, mechanical properties, and testing requirements.
2. What are the typical dimensional tolerances for Cold Drawn Pipe?
Answer: Tolerances are exceptionally tight. For example, a typical Cold Drawn DOM (Drawn Over Mandrel) tube might have an OD tolerance of ±0.005 inches (±0.127 mm) and a wall thickness tolerance of around ±10%. This is significantly tighter than hot-finished or welded-only tubing.
3. Can Cold Drawn Pipe be welded, and what are the considerations?
Answer: Yes, it can be welded. However, the work-hardened condition can lead to brittleness in the Heat-Affected Zone (HAZ). Proper procedures are critical, including:
Using a suitable welding technique (e.g., TIG for precision work).
Potentially pre-heating and controlling interpass temperature.
Often performing post-weld heat treatment to relieve stresses and restore toughness in the HAZ.
4. What is the difference between CDW (Cold Drawn Welded) and CDS (Cold Drawn Seamless) pipe?
Answer:
CDW (Cold Drawn Welded): Starts as a welded tube (from a strip or sheet), which is then cold-drawn. This process refines the weld seam and improves the overall dimensions and surface finish. It's a cost-effective option for many applications.
CDS (Cold Drawn Seamless): Starts as a hot-extruded seamless hollow, which is then cold-drawn. It has no longitudinal weld seam, making it the preferred choice for high-pressure applications where homogeneity is critical.
5. What are the key factors to consider when sourcing Cold Drawn Pipe?
Answer:
Material Grade and Specification: Ensure it meets the required standard (e.g., ASTM A513).
Dimensional Requirements: Confirm the OD, ID, wall thickness, and length tolerances.
Mechanical Properties: Verify the required yield strength, tensile strength, and hardness.
Heat Treatment Condition: Specify if you need it "as-drawn" (hard), stress-relieved, or annealed.
Surface Finish and Oiling: Determine if a specific surface roughness is needed and if anti-rust oil is required for protection.
