Determination of minimum thickness

According to the definition in GB150 Part 1, 3.1.14, the minimum forming thickness is the minimum thickness that must be maintained in a compressed component after forming to satisfy the design requirements. Personally, I think: minimum formable thickness = calculated thickness + corrosion allowance + negative deviation of material thickness. This method is more suitable for use by design firms. Section 4.3 on windward markings in GB25198 also provides two methods; the first method involves indicating the thickness with a pattern, and it should be determined using the approach mentioned above – yet the calculations based on the appendix do not yield consistent results. The second method involves marking the actual measurement values. If you are the manufacturing unit, you will certainly obtain a certificate for the end cap, which includes the actual measurement values as well as the required values; you can refer to these markings. (But it must meet your design requirements; the redundant design must satisfy your actual usage needs.) I asked the classmates in charge of supervision, but they didn’t provide any clear requirements either.

We generally calculate the acceptable thickness by subtracting the negative deviation from the nominal thickness and then subtracting the amount of thinning due to processing (in accordance with Appendix J of GB/T25198-2010), including reinforcement for openings.

I should also ask the security officer whether they have experience in design, 1. Calculate thickness + C1 + C2 + allowance; the first three values are fixed, while the allowance is determined by the designer. 2. If there are holes in the head, use the minimum thickness mentioned above to calculate the reinforcement for all openings. Passing is fine; just increase the margin for reinforcement. 3. For those with lifting lugs, calculate the local stress at the lugs; the approach is the same as in 2

Do not use this method. \ud83d\ude02 criticized us just this morning. The container expert questioned the designer: After determining the minimum forming thickness, have you calculated the thinning rate of the head? Designer:.......? ? No. Container expert: Think again about how to calculate it – do you really need the head factory to roll it to this thickness? Designer: He can’t reach it..... No, it’s not necessary.

On the drawings we used to produce, it was indicated as: nominal thickness (minimum formable thickness), such as 8 (7.7), where the minimum formable thickness is the nominal thickness minus the negative deviation. In the technical requirements, it should be specified: the thickness of the head material (if the nominal thickness is 8 mm, then a reduction of 10 mm should be taken into account for the actual material thickness); the nominal thickness is 8 mm, and the formed thickness should be ≥7.7 mm.

Let’s talk about personal practices: handshake. The calculated thickness is determined using software, taking into account the corrosion allowance, the negative deviation of the steel plate, the thinning resulting from head forming (the thinning rate can be obtained from head manufacturing standards or based on the experience of different head manufacturers), as well as the rounding up factor. A nominal thickness for the head is first established; this nominal thickness is entered into the software. The thinning amount of the head is added to the corrosion allowance and also entered into the software, so as to verify the nominal thickness of the head and calculate the reinforcement required for any openings in it. The MIN minimum thickness is the nominal thickness minus the amount of thinning that occurs during shaping. If the nominal thickness is 10 mm and the thinning rate is 15%, then the MIN minimum thickness should be 8.5 mm. On the drawings, this is indicated as 10MIN8.5; after the head is shaped, its minimum thickness will be 8.5 mm, as it is based on this thickness that the reinforcement for the head and openings is calculated.

This post was last edited by wanlirn on 10-10-2019 at 11:45; what is filled in the () is the design thickness, which is equal to the calculated thickness plus the corrosion allowance

This post was last edited by wanlirn on 2019-10-9 at 19:37. What you’re doing here is based on practices from over a decade ago; it’s clearly unreasonable. It eliminates the meaning of the head-forming reduction rate standards. It was precisely because there was no such concept as a minimum forming thickness in the past that issues arose during quoting, product standardization, manufacturing, flaw detection, and acceptance – issues such as problems related to allowable stress levels at increased thicknesses, waste resulting from secondary rounding, and so on. **That’s why this minimum forming thickness standard was introduced. It seems that training sessions on standard implementation are indeed useful

This post was last edited by wanlirn on 2019-10-9 at 19:36. What you’re doing here is based on practices from over a decade ago; it’s clearly unreasonable. It eliminates the meaning of the head-forming reduction rate standards. It was precisely because there was no such concept as a minimum forming thickness in the past that issues arose during quoting, product standardization, manufacturing, flaw detection, and acceptance – issues such as problems related to allowable stress values depending on thickness, waste resulting from secondary rounding, and so on. **That’s why this minimum forming thickness standard was introduced. It seems that training sessions on standard implementation are indeed useful