1. What are the surface treatments for seamless carbon steel pipes?
Common surface treatments:
* Black casing (original surface): Rust-preventive oil protection
* Painting: Red paint, yellow paint, blue paint, zinc-rich paint
* Powder coating, anti-corrosion coating
* Threading, beveling, flange welding pretreatment
* Export commonly uses rust-preventive oil + woven bags/wooden crates for packaging.
2. How to judge the quality of seamless carbon steel pipes?
Key points for judgment:
* Whether the material meets standards, providing material certificates, chemical composition, and mechanical properties
* Whether there are cracks, folds, scars, or pits on the inner and outer surfaces
* Whether the wall thickness is uniform and the ovality is qualified
* Whether the hydrostatic test and non-destructive testing are qualified
* Whether the dimensional accuracy, length, beveling, and chamfering meet the requirements
* Reputable manufacturers can provide complete test reports for each batch.
3. Do seamless carbon steel pipes need to undergo a hydrostatic test?
Yes. All seamless pipes used for fluids, boilers, and pipelines must undergo a hydrostatic test. The pipes are pressurized to standard pressure for a certain period of time; no leakage or deformation indicates qualification. We conduct 100% hydrostatic testing before shipment to ensure safe use.
4. Does seamless carbon steel pipe undergo non-destructive testing (UT/RT)?
Depending on customer and standard requirements, we can provide:
UT Ultrasonic Testing
MT Magnetic Particle Testing
ET Eddy Current Testing
Used to detect internal defects, surface cracks, and weld defects (seamless pipes primarily test for internal defects), ensuring safe use in high-pressure and high-risk environments.
5. What is the difference between 20# steel and Q355B? How to choose?
20#: High-quality carbon structural steel, good plasticity and toughness, easy to weld, suitable for fluid transportation and medium-to-low pressure pipelines.
Q355B: Low-alloy high-strength steel, higher strength and better load-bearing capacity, suitable for structures, machinery, supports, and engineering machinery.
Choose according to application: Choose 20# for media transport, choose Q355B for structural applications.
