2　Terms

2.0.1　Expanding

The process of using tools to expand a small hole already inside the billet to the size requested for extrusion.

2.0.2　Piercing

The process in which the solid billet is first put into a piercing container and upset with upsetting stem in order to make it fully occupy the inner space of the container.The next step is to use tools to pierce a through-hole along the center of the billet according to extrusion requirement.

2.0.3　Extruding

A production process，in which the billet is placed into a large vessel that consists of extrusion container，extrusion die，mandrel and dummy block；then extrusion force applied by extrusion stem will force metals flowing out along the interspace formed by extrusion die and mandrel to allow the billet to be extruded into pipe product.

2.0.4　Mill set

A package of all technological equipments that is necessary for the entire process，ranging from raw material preparation to end products which are specified in the product mix.

2.0.5　Annual necessary production time of mill set Annual actual production time that is necessary for achieving the annual production output as specified in the product mix.

2.0.6　Duty ratio of mill set

A percentage of actual annual working time to effective annual working time of the mill set.

2.0.7　On line

An operation mode in which a working stock can be transported to a designated working procedure from a continuously operated extrusion line，or vice versa，without the need of lifting and transport equipment and manual handling as well.

2.0.8　Visual examination

A method to observe the inside and outside surface of steel pipe with either naked eyes or simple tools like low-magnification magnifier or endoscopes to find out surface defect，if any.

2.0.9　Non-destructive testing

A general description of flaw detection methods without damaging properties and integrity of material or product to be tested.

2.0.10　Ultrasonic inspection

A non-destructive testing method of using ultrasonic to detect the inside and outside surface defect，if any.

2.0.11　Eddy current inspection

A flaw testing method to generate eddy current inside a conductive specimen，and then detect defect，if any，by measuring the variation of eddy current.

2.0.12　On line solution treatment

A heat treatment method to obtain supersaturated solid solution by utilizing fast cooling of the residual heat generated during pipe extrusion.