In daily steel purchases, the most annoying thing is the purchase
of low-quality seamless steel tubes, which affects product quality.
How to identify low-quality seamless steel tubes? Let's take a look
at the methods that can be used to identify high-quality seamless
steel pipes and inferior seamless steel pipes with the naked eye:
1. Inferior quality seamless steel pipes are prone to scars.
Mainly due to two reasons:
(1) Inferior seamless steel pipes have many impurities and uneven
materials.
(2) Inferior pipe manufacturers have simple guide and guard
equipment, which is especially easy to stick to steel, and the
pipes containing impurities are prone to scars after biting into
the roll.
| product name | Alloy Seamless Steel Pipe |
| standard | GB, JIS, DIN, ASTM, bs, GB 18248-2000, JIS G3463-2006 |
| Material | 10#.20#.45#15Mn.20Mn.45Mn.30Mn2 q235 A106 |
| packing | 1.Wrapped in waterproof paper of steel pipe tube
2.Sackcloth with several steel strips of steel pipe tube
3.Cover cap of steelpipe tube
4. Wooden case of steel pipe tube |
| size | OD 3-300MM wall thickness: 1-30MM |
| suface | 1. PVC, black and paint 2. Transparent oil and rust-proof oil
3. According to customer requirements |
| MOQ | 1TONS |
| Trade | T/T, 100% L/C at sight, Cash, Western Union are all accepted if you
have other payment,please contact me |
seamless pipe
2. Inferior quality seamless steel pipes are prone to pipe folding.
The so-called folding refers to the various fold lines formed on
the surface of seamless steel pipes. Such defects often run through
the longitudinal direction of the entire product. The reason for
the folding is that in order to increase the output, the
manufacturer pursues high efficiency, and the pressing amount is
too large during the production process, which produces ears, and
it is easy to produce folding in the next rolling process. The
folded product is prone to cracking after bending, which causes the
strength of the pipe to be greatly reduced.
3. Inferior quality seamless steel pipes are prone to scratches.
The reason is that the production equipment of inferior steel pipe
manufacturers is simple and the products are prone to burrs and
scratches on the surface of the steel. Deep scratches will reduce
the strength of the steel.
4. Inferior quality seamless steel pipes often have pitting on the
surface.
The pitted surface is a defect of irregular unevenness on the
surface of the steel due to severe wear of the rolling groove.
Because inferior steel pipe manufacturers are pursuing profits, the
groove rolling often exceeds the standard.
5. Inferior pipes are prone to cracks on the surface. One of the
reasons is that the blanks are adobes, which have many pores. In
the process of cooling, due to the effect of thermal stress, cracks
are generated, and there are cracks after rolling.
6. Inferior seamless steel pipes have no metallic luster and are
light red or similar to pig iron. There are two reasons:
(1) Its blank is adobe.
(2) The rolling temperature of low-quality materials is not
standard. Their steel temperature is visually inspected, so that
rolling cannot be carried out in the specified austenite area, and
the performance of the steel will naturally not meet the standard.
7. Inferior quality seamless steel pipes have thin and low
transverse ribs and often appear dissatisfied. The reason is that
in order to achieve a large negative tolerance, the reduction of
the first few passes of the finished product is too large, the iron
type is too small, and the hole type is not full.
seamless steel pipe- PMC
8. The composition of high-quality steel is uniform, the
specifications of the pipe cutting machine are high, and the end
face of the cutting head is smooth and tidy. However, due to the
poor material, the end face of the cutting head often has meat
loss, that is, it is uneven and has no metallic luster. Moreover,
because the products of inferior material manufacturers have fewer
cuts, big ears will appear at the beginning and the end.
9. Inferior seamless steel pipes have irregular cross-sections and
large ellipticity errors. The reason is that in order to increase
the output, the reduction of the first two passes of the finished
roll is too large for the manufacturer. The strength of this kind
of seamless steel pipe is greatly reduced, and it does not meet the
standard of seamless steel pipe dimensions.
10. The material of inferior seamless steel pipe contains many
impurities, the density of steel is too small, and the size is out
of tolerance seriously, so it can be weighed and checked without a
vernier caliper. For example, for rebar #20, the national standard
stipulates that the maximum negative tolerance is 5%. When the
fixed length is 9M, its single theoretical weight is 120 kg, and
its minimum weight should be: 120 X (l-5%) = 114 kilograms, the
actual weight of a single piece weighed out is smaller than 114
kilograms, it is inferior steel, because its negative tolerance
exceeds 5%. Generally speaking, the effect of phasing weighing will
be better, mainly considering the problem of cumulative error and
probability theory.
11. The inner diameter size of inferior seamless steel pipe
fluctuates greatly, the reason is:
(1) The steel temperature is unstable and has a yin and yang side.
(2) The composition of steel is not uniform.
(3) Due to the simple equipment and low foundation strength, the
rolling mill bounces greatly. There will be large changes in the
same week, and such seamless steel pipes are prone to breakage due
to uneven stress.
12. The trademarks and printing of high-quality seamless steel
pipes are relatively standardized.
13. Inferior seamless steel pipe manufacturers have loose packaging
because they have no driving. The side is oval
