What is a mandrel bar used for in seamless pipe production?

In MPM/PQF and similar continuous mills, the mandrel bar supports the pipe bore while external rolls reduce the wall. It travels with the shell through the stands, then is stripped, cooled, dressed and recirculated.

Why is H13 the common mandrel bar material?

H13 hot-work steel keeps hardness and resists heat checking at the 600 °C+ contact temperatures seen in each rolling cycle, giving the best balance of thermal fatigue life and toughness for long bars.

What HS code applies to mandrel bars?

As parts of metal-rolling mills, mandrel bars are generally classified under HS 8455.90.

Products /Mill Components

Mandrel Bar

Name: Mandrel Bar
Brand: Core Steel Works

A mandrel bar is a long, hardened alloy steel bar inserted inside a hollow shell during seamless pipe rolling. The pipe wall is rolled between the external rolls and the mandrel surface, so bar straightness, surface finish and thermal fatigue resistance directly determine pipe ID quality. Bars are forged, heat treated, deep-hole machined where required, and chrome plated.

HS 8455.90EN 10204 3.1 MTCISO 9001

Reference Specification

Mandrel Bar — reference data
Diameter	60 – 500 mm
Length	Up to 15 m
Straightness	≤ 0.5 mm/m, tighter on request
Surface	Ground and hard-chrome plated
Surface hardness	≥ 45 HRC typical, spec-dependent
Inspection	UT, straightness survey, hardness, plating thickness, MTC 3.1

Materials

· H13 (4Cr5MoSiV1) hot-work tool steel
· 30CrMoV / similar per mill practice

Mandrel Bar — product photo — photo pending

RFQ Checklist

Include this in your inquiry for a fast, accurate quote

01Bar drawing with diameter, length, tolerances and straightness
02Mill type (MPM, PQF, Assel, plug mill) and pipe size range
03Material grade and hardness/plating specification
04Quantity per size and annual consumption
05Delivery schedule and packing requirements (long-bar export frames)

Send RFQ / Upload Drawing

The consumable that defines bore quality

Mandrel bars are working consumables: every pass exposes them to hot shell friction and quench cycles. Scoring or heat-check on the bar prints directly onto the pipe ID. Consistent bar metallurgy and plating quality translate to fewer bore defects and longer campaign lengths.

Export packing

Bars up to 15 m ship in purpose-built steel frames with end protection and VCI wrapping — packing drawings are provided for approval before shipment.

Frequently Asked Questions

What is a mandrel bar used for in seamless pipe production?: In MPM/PQF and similar continuous mills, the mandrel bar supports the pipe bore while external rolls reduce the wall. It travels with the shell through the stands, then is stripped, cooled, dressed and recirculated.
Why is H13 the common mandrel bar material?: H13 hot-work steel keeps hardness and resists heat checking at the 600 °C+ contact temperatures seen in each rolling cycle, giving the best balance of thermal fatigue life and toughness for long bars.
What HS code applies to mandrel bars?: As parts of metal-rolling mills, mandrel bars are generally classified under HS 8455.90.