4 requirements for stainless steel square tubes for mechanical equipment

To ensure that stainless steel square tubes for mechanical equipment meet the stringent requirements of mechanical equipment in terms of strength, precision, and durability, the four quality requirements are as follows:

 

 

1. Wall thickness requirements (sufficient thickness)

Standard basis: Select the corresponding standard (such as GB/T 3094-2012, ASTM A554, etc.) according to the application scenario, and clarify the wall thickness tolerance range (conventional wall thickness ±0.02 mm).

 

Material selection:

General environment: 304 stainless steel (06Cr19Ni10), with a balance of corrosion resistance and strength.

Highly corrosive environment: 316L stainless steel (022Cr17Ni12Mo2), containing molybdenum to improve pitting resistance.

High strength requirements: Duplex stainless steel 2205 (S32205) can be selected, with a yield strength of more than 450MPa.

 

Key control points:

Raw material storage inspection: Full inspection of the raw material steel strip thickness gauge to ensure that the incoming material thickness meets the standard.

Forming process monitoring: avoid local thinning caused by cold bending, and strictly control the R angle area.

 

2. Full penetration of the weld (weld penetration)

The weld of each stainless steel square tube for the mechanical equipment of Jude Steel is fully penetrated.

Nitrogen inside the weld is used for protection: to prevent weld oxidation and reduce the probability of subsequent weld rust.

Online monitoring: equipped with an infrared thermal imager to monitor the weld temperature field in real time.

 

3. R angle uniformity control

Forming process optimization:

Use a four-roll cold bending forming machine, the R angle radius and wall thickness ratio ≥1.5 (such as t=3mm, R≥4.5mm).

Multi-pass progressive forming: bend gradually in 4-6 passes to reduce stress concentration.

 

Dimension detection:

The R angle size of stainless steel square tubes for mechanical equipment is fully inspected.

Quick sampling to ensure that the symmetry of the four corners meets the standard.

 

4. Straightness and twist control

Key points:

Straightening process: Use a seven-roll straightening machine, and the straightening force is set according to the yield strength of the pipe (such as 304 stainless steel needs ≥200MPa).

Straightness detection:

Online measurement with a straightness meter strictly controls the deviation value per meter.

Platform with feeler gauge method: Place the square tube on a horizontal plane to measure the local gap.

 

5. Full process quality control plan

1. Raw materials: material report (including spectral analysis), verify the Cr/Ni/Mo content.

 

2. Pipe-making process:

Full-size inspection of the first piece (wall thickness, R angle, weld).

Randomly check straightness and surface quality every hour.

 

3. Finished product inspection:

Accessory test: The corresponding accessories are directly outer or inner plugged to measure the size of the square tube, R angle, etc.

Salt spray test: neutral salt spray test, standard 304 stainless steel pipe 48-72 hours, standard 316 stainless steel 72-120 hours.

 

Stainless steel pipe manufacturer Jude Steel recommends that you choose suitable stainless steel square tubes for mechanical equipment according to specific usage scenarios.

Mob: +86-13772502581
Email: Judesteel@Juqing.Hk