Keeping on top of tubes
Here, Stewart Jones, Customer Technical Services Engineer, Conveyance Tubes at Tata Steel discusses why continued professional development courses play a crucial role in keeping engineers up to date with the evolution of hot-finished tubes as well as legislative changes.
Within the building services sector, it is important to be aware of the different manufacturing processes used to produce carbon steel tubes in order to ensure that the most suitable product is then specified for projects.
Clear differences exist in the manufacturing of steel tube products, with the two main methods producing either cold-formed or hot-finished tubes. For cold-formed tubes, the pipe is produced from a steel strip that is shaped when cold and welded. However, throughout this process the steel hardens due to both the cold working and welding processes, which introduces internal stresses to the tube.
The region adjacent to the weld seam, which is known as the Heat Affected Zone (HAZ), is particularly highly stressed. This is due to the heat from the welding process distorting the steel’s internal grain structure, which makes it harder and less malleable. Consequently, the level of internal stress may rise even further if any fabrication or manipulation occurs during installation. As well as increasing the risk of cracking or failing in service, such additional fabrication also significantly increases the product’s vulnerability to stress induced corrosion.
Hot-finished tube production adopts a similar approach to that of cold-formed – with one essential additional step that removes the internal stresses from the product. Following the welding of the tube, it is then heated to a very high temperature using induction or furnace heating. This effectively removes the internal stress and eradicates the distorted grain structure of the HAZ.
Hot-finished tubes therefore offer a multitude of benefits over their cold-formed counterparts:
- A more ordered and consistent microstructure
- No internal stresses that can promote cracking
- More consistent and reliable mechanical properties
- Improved structural integrity and ductility
- An improved and more consistent toughness
- Higher pressure integrity
- A greater safety factor
- No strength loss when subjected to extra welding or heating
- Enhanced performance against corrosion
- The ability to be threaded, grooved or bent to a tighter radius – removing any risk of splitting, creasing or collapsing
In addition to the general lack of understanding about the different tube manufacturing processes, updates in legislation have also left some specifiers and engineers unclear as to what are the latest and most accurate tube standards to specify.
For example, the BS1387 standard is still often quoted within project specifications. However, this standard was withdrawn in 2004, and replaced with BS EN10255. It is important to note that specifying this new standard alone will not ensure a hot-finished tube. To guarantee this, a multi-certified approach needs to be adopted and along with BS EN 10255 a BS EN10217 Part 2 compliant product must also be requested. Only by also specifying BS EN10217-2 can the supply of a GH (Get Hot) product be guaranteed.
Some commodity, imported tubes may appear to be CE marked to the Construction Products Regulations, but this may not be the actual case. Therefore, in order to guarantee that the tube is fit-for-purpose, it is essential to ensure that the correct compliance information and references to third party approval of the manufacturing and testing procedures is provided. It is the responsibility of the manufacturer, or for imported products, the stockholder or local Agent, to provide information to confirm that the tube product is fully CE marked for both CAT3 (fuel and gas) and CAT4 (water).
To avoid confusion and ensure that engineers are up-to-date with both industry legislation and manufacturing innovation, it is important to regularly attend Continued Professional Development (CPD) courses.
Demonstrating the essentials and importance of tube manufacturing – while raising awareness of legislative changes and industry issues – Tata Steel, in collaboration with the School of Architecture, Building and Civil Engineering, Loughborough University, has founded the Building and Industrial Services Pipework Academy (BISPA). By providing training and CPD programmes based upon industry issues such as specifications and hot-finished tube benefits, BISPA has a clear function in supporting the building and industrial services industry from both its base in Loughborough, and from its satellite campus at the Olympic Park, London.
Catering for various knowledge levels from novice to advanced, BISPA also offers a practical environment to refine and hone skills, alongside a classroom environment for attendees to consume current technical and legislative information. Providing BIM modelling software, pipework rigs and specifications, the BISPA centre and its CPD programme incorporates key industry elements to aid building services engineers’ career development and reduce project risks.
BISPA is pleased to be supporting the BSEE Building Services Forum, at the Building Center in London. At the venue, BISPA will also be running a number of free CPD taster events on the 8th and 9th February 2018.