How to Avoid Cracking During Gas Cylinder Steel Stamping
Stamping cracking is one of the most common and costly problems when manufacturing LPG, CNG, or industrial gas cylinders. Even when using standard-compliant materials like JIS G3116 SG295 or SG255, improper stamping parameters can lead to reject rates above 5% – or even dangerous field failures.
Start with the Right Steel Grade – Don't Over-Optimize for Cost
| Steel Grade | Yield Strength (MPa) | Typical Elongation | Suitability for Cylinder Stamping |
|---|---|---|---|
| SG295 | ≥295 | ≥26% | Recommended – good balance of strength and formability |
| SG255 | ≥255 | ≥28% | Suitable for low-pressure or small-diameter cylinders |
| Q235B | ≥235 | ≥26% | Not recommended – not certified for gas cylinders, higher cracking risk |
✅ Key takeaway: Using a grade with consistent yield strength (e.g., SG295 with typical 310–340 MPa) is safer than using a cheaper, non-specialized steel with wide property variation.
Strictly Control the Blanking and Edge Quality
Cracks often start from micro-defects on the blank edge.
Inspect blank edges: No burrs >0.2mm, no scabs, no visible laminations.
Avoid shearing-induced work hardening: If possible, use laser cutting or fine blanking for high-precision blanks.
Deburring: Lightly grind or tumble blanks to remove sharp edges before stamping.
Optimize the Drawing Ratio and Multi-Step Stamping
Most cylinder heads are formed by deep drawing. If the drawing ratio is too high for a single step, cracking becomes inevitable.
Single-step drawing
Suitable for shallow parts (draw ratio <1.8).
Multi-step drawing (2 or 3 steps)
Required for typical cylinder heads with draw ratio >2.0.
Intermediate annealing:
If more than 2 draws are needed, perform annealing between steps to restore ductility.
why choose us?
Response time: Inquiry answered within 24 hours (often same day).
Technical support: Stamping parameter recommendations, cracking troubleshooting.
Heat number traceability from our warehouse to your production floor.
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Choose YUXIN steel group, and what you purchase is not merely the steel plates, but also a complete warranty system and a sense of responsibility.
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Tianjin, China
Phone Number
(86)-15937221771(WeChat)
(86)-15837212056(WhatsApp)
info@chinasteelcompany.com
FAQ
01.Does your SG295 steel comply with Vietnam's QCVN technical regulations for gas cylinders?
Yes. Our SG295 steel is strictly manufactured according to JIS G3116:2020, which is the recognized technical basis for QCVN conformity assessment in Vietnam.
We provide full documentation to support your declaration of conformity, including:
Original Mill Test Certificate (MTC) with heat number traceability
Chemical composition and mechanical test reports
JIS G3116 compliance statement
02.What is the difference between SG295 and SG255? Which one should I choose for LPG cylinders?
| Parameter | SG295 | SG255 |
|---|---|---|
| Minimum yield strength | 295 MPa | 255 MPa |
| Minimum tensile strength | 440 MPa | 400 MPa |
| Elongation | ≥26% | ≥28% |
| Typical use | LPG/CNG cylinders (up to 500L) | Low-pressure vessels, simpler stampings |
Our recommendation:
For standard LPG cylinders (12.5kg, 50kg) – choose SG295. Its higher strength allows thinner cylinder walls, saving material weight.
For very low-pressure applications or small-diameter cylinders – SG255 may be sufficient.
✅ Most Vietnamese gas cylinder manufacturers use SG295 as the minimum grade for QCVN compliance.
03.What is your minimum order quantity (MOQ)? Can I place a trial order before committing to bulk purchase?
Yes, we support trial orders. We understand you want to verify quality before large commitments.
| Order Type | Quantity | Lead Time |
|---|---|---|
| Trial order | 1–2 rolls (approx. 3–8 tons) | From stock – 3 to 5 days |
| Custom rolling | 20 tons minimum (one heat number) | 20–25 days |
| Bulk vessel | 200–500 tons | Negotiated |
💡 New customer tip: Many of our long-term partners started with a single roll trial order to test our material consistency, documentation accuracy, and logistics support.
04.Do you support third-party pre-shipment inspections (SGS, BV, Intertek, TÜV)?
Yes, we fully support and coordinate pre-shipment inspections by any internationally recognized agency.
We work with:
SGS – Sampling, testing, and report issuance
Bureau Veritas (BV) – Full inspection coordination
Intertek – Test documentation for customs
TÜV – Technical file preparation
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Through years of understanding and precipitation of steel, Yuxin Group has now become a mature steel processing and manufacturer, providing various products for many construction companies and steel structure companies around the world. Thanks to Yuxin Group's professionalism and integrity, it has become a world-renowned enterprise.
