1. Indefinite length (usually length)
The lengths of galvanized seamless steel pipes are generally of different lengths, and those within the scope of the standard are called variable lengths. The length of an indefinite ruler is also called the usual length (through ruler). For example, the usual length of 159*4.5 galvanized seamless steel pipe is 8 to 12.5

2. Fixed length
Cut to a fixed size according to order requirements is called fixed length. When delivered in fixed length, the delivered galvanized seamless steel pipe must have the length specified by the purchaser in the order contract. For example, if the contract states that the delivery is to be in a fixed length of 6m, the delivered materials must all be 6m long. Anything shorter than 6m or longer than 6m will be deemed unqualified. However, all deliveries cannot be 6m long, so it is stipulated that positive deviations are allowed, but negative deviations are not allowed. (When the fixed length is not greater than 6m, the allowable deviation is expanded to +30mm; when the fixed length is greater than 6m, the allowable deviation is expanded to +50mm)

3. Multiplier
Those cut into integral multiples according to the fixed size required by the order are called double rulers. When delivering goods in multiple lengths, the length of the delivered galvanized seamless steel pipe must be an integer multiple of the length (called single length) specified by the purchaser in the order contract (plus saw kerf). For example, if the buyer requires the length of a single ruler to be 2m in the order contract, then the length will be 4m when cut into a double ruler, 6m when cut into a triple ruler, and one or two saw kerfs will be added respectively. The amount of saw kerf is specified in the standard. When the scale is delivered, only positive deviations are allowed, and negative deviations are not allowed.

4. Short ruler
A ruler whose length is less than the lower limit of the indefinite ruler specified in the standard, but not less than the shortest length allowed, is called a short ruler. For example, the fluid transportation steel pipe standard stipulates that each batch is allowed to have 10% (calculated by number) of short-length steel pipes with a length of 2-4m. 4m is the lower limit of the indefinite length, and the shortest length allowed is 2m.