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Why can’t you ship my steel on a container to reduce transit time?
We would always like to put steel on a container ship as in almost all circumstances it is both faster and cheaper. The limitation is size, and less rarely weight. The width of a container is 2200mm. Some space needs to be left to allow it to be unstuffed easily but given that a lot of plates are either 2500mm or 3500mm wide this means that they have to be shipped by conventional vessel.
In the past some shipping companies allowed steel plates to be placed at an angle which allowed plates up to 3000mm to be shipped in a container. This saved money and time for everyone apart from the shipping companies because containers often got damaged.
One way of fitting large plates into containers is to cut them down. This is a decision that has to come from the design team or the engineers – but the cost saving will often be worth the time in asking the question.
Why do you offer me an equivalent steel grade?
For historical reasons a lot of countries have their own standards that specify the requirements for steel. BS in the UK, JIS in Japan, DIN in Germany for example. The laws of physics don’t reflect national boundaries and engineers find themselves solving the same problems across the world.
When they have a need for a steel with certain characteristics – say a very low phosphorous content – engineers in other countries will have had the same requirement and in both places very similar steel will be produced differing only in the name that is given to it.
There are two types of equivalent steel grade. The first is where the relevant standards have been harmonised, for example in boiler quality steel A 516 and SA 516 are the same and totally interchangeable. The other case is where the standards are equivalent BS 224–490B is equivalent to
A 516 70. In this case a sample material test certificate is provided to allow the sourcing engineer to confirm that the material offered will meet the engineering requirements of the job.
Mills generally produce to their preferred standard. For example say a mill regularly produces A 516 70 and it is asked to roll a batch of P 355GH. Instead of produced P 355 GH it is likely to produce the A 516 70 and then dual certify it to P 355 GH. This means that it has not additional set up costs for the production, but still satisfies the needs of its end user. (note: there is usually an additional charge for dual or re–certification.)
Why is the Mill Test Certificate (MTC) so important?
Walking through a steel mill is impressive but as a visitor all you can say is that they are making steel. By the time that you have finished the tour of the mill you can say that they are manufacturing plate or coil but from a visual inspection you can say little more. The same is true when you walk through a warehouse full of steel. There are lots of stacks of plate but to the naked eye there is no way of telling the difference between boiler quality plate and structural plate (unless you know the colour codes used in the warehouse).
The MTC tells you everything that you need to know about the steel. I have an MTC from a French mill in front of me for A 516 70. For each heat number it gives me the number of plates, and their performance in tensile and notch toughness tests. It also gives me the chemical composition for each heat. This certificate then tells me that the plate is fit for purpose and the heat number stamped on the plate ties the two together.
Without an MTC a plate is worth little more than scrap without extensive retesting and chemical analysis. With it the plate has a passport into a boiler or a bridge and the MTC will form part of the quality documentation that proves that the construction needs all the required standards and specifications.
Finally the mill test certificate offers full traceability for the steel.
Quality steel supplied for:
oil & gas, petrochemical & process,construction & shipbuilding industries
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