Precision Steel Tube Bright Thick Wall Seamless Steel Tube 45# Seamless Tube

Precision Steel Tube Bright Thick Wall Seamless Steel Tube 45# Seamless Tube Wholesale Support Cutting

The length of delivery
Delivery length is also called customer required length or contract length. The standard has the following provisions on delivery length:
A, ordinary length (also known as irregular length) : where the length is within the standard length range and there is no fixed length requirements, are called ordinary length. For example, structural pipe standards: hot rolled (extruded, expanded) steel pipe 3000mm ~ 12000mm; Cold-drawn (rolled) steel pipe 2000mm ~ 10500mm.
B. Fixed length: the fixed length shall be within the normal length range and is a fixed length specified in the contract. But in practice, it is impossible to cut absolute length, so the standard stipulates the allowable positive deviation value for the length of definite length.
The structural pipe standard is:
The yield of fixed length pipe decreases more than that of normal length pipe, so it is reasonable for the manufacturer to raise the price. Add price range each enterprise is not consistent, add price 10% or so on base price foundation commonly.
C. Length of multiples: the length of multiples shall be within the normal length range, and the single length and the multiple of the total length shall be indicated in the contract (e.g. 3000mm×3, i.e. 3000mm 3x, with a total length of 9000mm). In practice, the allowable positive deviation of 20mm should be added to the total length, plus the incision allowance should be left for each single ruler length. Take the structural pipe as an example, the specified incision allowance: outer diameter ≤159mm is 5 ~ 10mm; Outer diameter >159mm is 10 ~ 15mm.
If there is no length deviation and cutting allowance in the standard, it shall be indicated in the contract through negotiation between the supply and demand parties. Double ruler length is the same as fixed ruler length, which will greatly reduce the yield of production enterprises. Therefore, it is reasonable for the production enterprises to raise the price, which is basically the same as the fixed ruler length.
D. Range length: the range length is within the usual range. If the user requires a fixed range length, it shall be indicated in the contract.
For example, the length ranges from 3000 mm to 12000mm, and the length ranges from 6000 mm to 8000mm or 8000mm to 10000mm.
It can be seen that the range length is more relaxed than fixed length and multiple length, but it is much stricter than the usual length, which will also reduce the yield of production enterprises. Because this production enterprise puts forward add price is reasonable, its add price range is in base price commonly add price 4% left and right sides.
Uneven wall thickness
Steel tube wall thickness can not be the same everywhere, there is an objective phenomenon of unequal wall thickness in its cross section and longitudinal tube body, that is, uneven wall thickness. In order to control this unevenness, the allowable index of wall thickness unevenness is stipulated in some steel pipe standards. Generally, it is not more than 80% of wall thickness tolerance (implemented after negotiation between the supply and demand parties).
ovality
The phenomenon of unequal outer diameters exists in the cross section of circular steel pipe, that is, the difference between the maximum outer diameter and the minimum outer diameter is ellipticity (or unroundness). In order to control the ovality, some steel pipe standards stipulate the allowable index of the ovality, which is generally not more than 80% of the outer diameter tolerance (implemented after negotiation between the supply and demand parties).
bending
The length of the steel pipe is curvilinear, and its curvilinear degree is called bending degree. The bending specified in the standard is generally divided into the following two kinds:
A. Local bending: measure the maximum bending point of the steel pipe with A one-meter ruler and measure its chord height (mm), which is the value of local bending. The unit is mm/m and the expression method is as follows: 2.5mm/m. This method also applies to pipe end bending.
B. Total bending of the whole length: measure the maximum chord height (mm) at the bending point of the steel pipe with a thin rope, and then convert the percentage of length (in meters) to the total bending of the length direction of the steel pipe.
For example: the length of steel pipe is 8m, and the maximum chord height measured is 30mm, then the full length bending of the pipe should be 0.03÷8m×100%=0.375%