The taken care of length required by the order is cut right into integral multiples called multiple sizes, which must be within the normal length array. Steel pipelines provided at several lengths should be of the length (solitary feet) or integer multiples (saws is added) defined in the order contract. For example, in the order agreement, the purchaser requires a single foot size of 2m, after that a dual foot length of 4m, or 3 times the size of 6m, and a notch margin for each and every single foot length, which specified in the standard. As an example, the external size ≤ 159mm, the margin of incision is 5 ~ 10mm; The outer diameter > 159mm is 10 ~ 15mm. If there is no multiple size inconsistency and cutting allowance in the requirement, it shall be negotiated by both events and indicated in the contract. Double size scale will substantially minimize the rate of steel pipeline makers as long as taken care of size.