Polysoude TS 8/75 Tube-to-Tubesheet Welding Head

Overview

The Polysoude TS 8/75 is an open orbital TIG welding head designed for welding tubes into tubesheets, the joint that holds every shell-and-tube heat exchanger, boiler, condenser and air cooler together. It welds with or without filler wire and carries arc voltage control (AVC) as standard. Its name reflects its working range: it handles tubes from a minimum inside diameter of 8 mm up to a maximum outside diameter of 75 mm, with outside diameters above 60 mm available on request. The manufacturer describes the head as compact, lightweight and easy to manoeuvre, with handles that carry integrated controls for clamping and welding.

Seven Star LLC supplies the Polysoude TS 8/75, its tooling and matching power sources to heat exchanger fabricators, refinery turnaround contractors and power plant maintenance teams in Oman and across the GCC, with engineering support from Muscat.

Operating Principle

Unlike pipe-to-pipe orbital welding, tube-to-tubesheet welding is done from the face of the tubesheet. The Polysoude TS 8/75 is centred inside the tube bore by a mandrel, and the torch then rotates around the tube end to fuse it to the tubesheet. Depending on the design, the joint can be flush, recessed, low protruding or protruding, and the head can also be configured for internal bore welding and for back plate or header box welding. The brochure lists recesses of up to 2 mm and protrusions of up to 13 mm among the supported joint designs.

A unique rotating collector feeds welding current, shielding gas and cooling liquid to the rotating torch, so the head can turn continuously without twisting its cables. Motorised AVC keeps the arc length constant by adjusting electrode height during the weld, and an encoder provides position-based control of the welding programme. Rotation runs under closed loop regulation for precise, constant or pulsed welding speed, and a return-to-home feature brings the electrode back to its starting position after each joint, ready for the next tube. In general, this kind of automation is what allows a tubesheet with hundreds of joints to be welded with uniform quality.

Engineering Design of the Polysoude TS 8/75

The head weighs 7.5 kg without bundle and wire spool, and is connected through a 9 m cable bundle. It is rated for 250 A at 60 percent duty cycle and 190 A at 100 percent, with closed loop water and glycol cooling, and the brochure notes cutting-edge design using temperature resistant materials for high duty cycle work. AVC stroke is 20 mm, and the torch uses a ceramic nozzle and diffuser for laminar gas protection. Adjustable stand-off legs allow the head to sit on any tube pitch, with torch angle settings of 0, 30, 45, 60, 90 and 120 degrees shown in the dimension drawing.

Several centring options are available for the Polysoude TS 8/75. A centring shaft with a two-ball mandrel covers inside diameters from 10.5 to 60 mm; the standard pneumatic centring and clamping system covers 15 to 40 mm; and a reinforced pneumatic device covers 40 to 60 mm. Filler wire can come from a rotating on-board wire feeder holding a 1.5 kg spool of 100 mm diameter, or from an external Polyfil compact or Polyfil-3 feeder holding up to 15 kg. Maximum wire feed speed is 1154 mm/min with PC series power sources or 2085 mm/min with the P6 series.

Key Features

The design points of the Polysoude TS 8/75 highlighted in the manufacturer brochure are summarised below.

• Tube range from 8 mm minimum ID to 75 mm maximum OD, OD above 60 mm on request.
• Rated 250 A at 60 percent and 190 A at 100 percent duty cycle with water and glycol cooling.
• Motorised arc voltage control with 20 mm stroke, or programmable electrode height.
• Rotating on-board wire feeder for precise, constant feeding, or external Polyfil feeders.
• Pneumatic centring and clamping as standard, with mandrels for all tube inside diameters.
• Flush, recessed, low protruding and protruding joints as standard; bore and header box welding as options.
• Integrated remote control on the handle for clamping and welding, plus simplified wire guide.
• Simultaneous use of multiple heads with integrated pneumatic tube clamping to raise productivity.

Industrial Applications

For the Polysoude TS 8/75 the market is broad: heat exchangers are everywhere in the Oman energy chain: gas processing trains, refinery crude and hydrotreater units, LNG facilities, petrochemical crackers, combined-cycle power plants and thermal desalination units. New bundles are fabricated to code, and existing bundles are retubed during shutdowns, often under tight schedules. The Polysoude TS 8/75 lets fabricators and turnaround contractors weld tube ends consistently, and its compact 7.5 kg body and adjustable legs are useful when working on a vertical tubesheet in the field.

The head is designed to run with the Polysoude P6 smart welding station, which the brochure recommends with arc voltage control and three-phase supply. Seven Star LLC supplies the Polysoude TS 8/75, P6 station, mandrels and tungsten electrodes to customers in Muscat, Sohar, Duqm, Salalah and the GCC.

See thePolysoude P6 smart welding stationfor the matching power source.

Technical Specifications

The data below for the Polysoude TS 8/75 is taken from the manufacturer brochure.

Accessories for the Polysoude TS 8/75 include clamping and centring mandrels for all tube IDs, a 15 m extension cable, a compact shipping case, pre-sharpened and pre-cut tungsten electrodes and application tooling.

Call To Action

To quote the Polysoude TS 8/75, Seven Star LLC needs your tube OD and wall thickness, tube and tubesheet materials, joint design and pitch. Our engineers in Muscat will confirm the mandrels, wire feed arrangement and power source. Download the manufacturer brochure on this page and contact us for supply in Oman and the GCC.