Product Description
seamless pipes grades and production methods
1. Round bar making Hollow Baraccording to customer's demanded material to produce the round bar, then making annealled heat treatment, then drill the hole as customer demanded inner diameter into the round bar, round bar piercing, making rough hole, then make precision processing to make outer diameter and inner diameter as requested. Any size hollow bar can be produced as demanded.
Tolerance for hollow round bar, forged round bar drilling hole hollow bar ASME SA530
| Type | Outer diameter(inner diameter) | Allowed tolerance | Wall thickness allowed tolerance |
Outer diameter | ≥219-457.2mm | -0.8 - +2.4mm | -0.8 - +4.0mm |
| >457.2-660.4mm | -0.8 - +3.2mm | ||
| >660.4-863.6mm | -0.8 - +4.0mm | ||
| >863.6mm | -0.8 - +4.8mm | ||
| Inner diameter | All size | -1.6- 0mm | 0 - +3.2mm |
Round bar making Hollow bar cost is high
2. Hot rolled Hollow Bar
using hot rolled steel pipe billet to make heating and piercing, elongating, sizing and stranghtening, cooling, finally hollow bars finished, this is the type most commonly used. Because it is hot rolled, so cost is lowest, but it is suit for large quantity, for small quantity, have to make cold drawn or round bar piercing. size: outer diameter 32mm- 499mm, wall thickness 4mm- 80mm
3. Cold drawn Hollow Bar
for outer diameter not over than 63.5mm, small size hollow bar, when demanded quantity is under 5 tons, usually make cold drawn hollow bar, using larger size hot rolled hollow bar to draw to the size demanded.
some size can be finished only by one time drawing, but some other sizes might need twice or three times to finish drawing, it takes time, so the cost is higher.
cold drawn size outer diameter 32mm- 63.5mm
4. Hot- expanding Hollow Bar
For hollow bar sizes are special, not common sizes, have to use smaller thick wall hollow bar to hot expand to be larger size hollow bar, but the technical property for hot-expanded hollow bar will be lower than the original hollow bar. Size: outer diameter over 356mm.
the seamless pipe grades can be supplied
Seamless Steel pipe grades
| Descriptions | Grades |
| Structural pipe | 20# 35# 45# Q345B, 16Mn, Q345B-E, 20Mn2, 25Mn, 30Mn2, 40Mn2, 45Mn2 SAE1018, SAE1020, SAE1518, SAE1045. |
| Liquid pipe | 20# q295b-e, q345b-e |
| High pressure boiler tube | 20G 15MnG 20MnG 15CrMoG, 12Cr1MoVG St35.8, sa106b, sa106c, sa210a, sa210c, A333P2, A333P11, A33P12, A333P22, A33P36, A333P91, A333P92, A335T2, A335T11, A335T12, A335T22, A335T91, A335T23, A335T9 |
| Pipeline | API SPEC 5L, X42, X52, X60, X65,X70,X80 ASTMA53, ASTM A106, ASTM A333, BS301, BS3602, BS3603, BS3604, PSL1, PSL2, DNV-OS-F101, CSA-Z245 |
| Alloy pipe | 4140, 42CrMo, 32CrMo, 15CrMo, |
| Packing | Black paint, Varnish painting, Tarpaulin packing |
| End | Common round end, beveled. |
| Processing | Galvanizing; cutting; making thread outside the pipe; Machining. |
| outer diameter | 16mm- 800mm |
| wall thickness | 4mm- 80mm |
Technological Process
Mill Test or Inspection
Packing & Deliver
Packing & DeliverPackaging & Shippin
Q1: Are you trading company or manufacturer ?
A: We are a factory. Our factory locates in Shandong Province. If you would like to visit our factory, just inform us in advance, we warmly welcome all of our clients to visit us.
Q2: How long is your delivery time?
A: Generally, it is 10-15 days after receiving the deposit.
Q3: What is your terms of payment?
A: T/T 30% as deposit, and 70% before delivery. We'll show you the photos of the products and packages before you pay the balance.
Q4: What is your terms of delivery?
A: EXW, FOB, CFR, CIF, etc.
Q5: What is your sample policy?
A: We can supply free samples if we have ready parts in stock, but the courier cost are charged.
Q6: what is your main products?
A: Our main products are listed as follows: Precision steel pipe, Hot Rolled steel pipe, Cold Drawn steel pipe, Seamless steel pipe, Alloy steel pipe, Bearing steel pipe, Welded pipe, Spiral pipe, Galvanized pipe etc.
A: Our main products are listed as follows: Precision steel pipe, Hot Rolled steel pipe, Cold Drawn steel pipe, Seamless steel pipe, Alloy steel pipe, Bearing steel pipe, Welded pipe, Spiral pipe, Galvanized pipe etc.