TPi May 2019

Products & developments

Long-distance weld purge monitoring When welding lengths of tubes and pipework fabrications of 20m or more, measuring the purge gas is not always easy. Under these conditions there is a risk of contamination of the gas exiting the weld zone, leaving the welders uncertain about the welds and welding procedure.

Weld purging expert Huntingdon Fusion Techniques (HFT) has designed and developed the PurgEye ® 1000 – a localised sensor with long-distance cable that displays the oxygen level in the welding zone on a Weld Purge Monitor ® screen that might be 10, 50 or even 1,000m away from the weld. Luke Keane, technical sales manager for HFT, explained, “By using a remote sensing head, which can be fitted onto any mechanical or inflatable tube and pipe weld purging system from 25mm (1") diameter upwards, or even left in the welding zone, the oxygen level can then be measured directly at the weld location and the information will be electronically transferred to the monitor up to 1 km away. With this capability, the operator can be certain that the weld purge reading is correct and that the joint will not be adversely affected by oxidation.” The PurgEye 1000 is one of five HFT weld purge monitors to feature PurgeNet™, a networking device designed for communicating the current oxygen reading from the monitor to another piece of equipment, such as the visual warning accessory PurgeAlarm™or a dew point monitor with additional inter-pass temperature monitoring. The sensor measures oxygen levels from 1,000 parts per million (ppm), down to 1 ppm (accurate to 10 ppm), making it suitable for welding metals such as stainless steels, duplex steels, titanium and zirconium where oxide-free, zero-colour welds are required. Without a remote sensor, weld purge exhaust gas would be piped down a hose to a distant measuring instrument, taking many minutes or even hours to reach a stable reading. The exhaust gas might even be contaminated on the way, by outgassing from the walls of the hose material or from air drawn in through a leaky connection. This would cause uncertain delays in reaching correct oxygen readings, making the process longer than necessary, and could even fail to

Visual alarm

give timely changes in oxygen levels in the weld zone. In the event that the oxygen level is too high, the weld would become oxidised and might even have nitrogen and hydrogen absorbed into the joint, which could cause metallurgical defects. Huntingdon Fusion Techniques – UK

hft@huntingdonfusion.com www.huntingdonfusion.com

PurgEye Remote, with pipe and sensing head

39

www.read-tpi.com

May 2019 TUBE PRODUCTS INTERNATIONAL