How to do a better weld

Minor tips on welding

    *   Set up the equipment. If necessary, erect a welding tent to protect against rainfall, wind and dust, conduct a trial before actual works to ensure the equipment in good working order

  *   Hold the pipes by clamps, one pipe fixed and one pipe is free to move such that they can be pressed against each other in single direction, then trimming/milling the joint faces

  *   Stop milling/trimming when joint surfaces are plain, even and crack free

  * Check for pipe alignment radially; by bringing the joint faces together. (Max Gap = 0.5mm).

  *   Check for pipe alignment axially in line with wall thickness. 

  *   Clean heating plate with lint free cloth and water/clear spirits.

  *   Check the welding temperature. (Recommended by manufacturer)

  *   Heat up and insert the plate between joint surfaces.

  *  Exert the heating pressure by the hydraulic unit until a bead is formed along the circumference of the joint faces.

  *   Reduce pressure to allow for heat dissipation into wall of pipe axially. (Soaking period).

  *   Remove heating plate over the allocated time and cover it properly to avoid contact with human or any substance,

  *   Press joint faces together, ensuring that the change-over time is not exceeded.

  *   Steadily increase the welding pressure to its allocated value.

  *   Keep at this pressure for the allocated time.

  *   Allow for cooling down at the welding pressure over the allocated time.

  *   (Never remove a weld from the machine before the cooling time has elapsed).

  *   When this cooling time has elapsed, reduce pressure to 0 and remove welded joint from clamps.

  *   Record the joint vs the pipe number, keep record for the jointing.

  *   If malpractice happened at any stage of the process, since the pre-heated PE material is not supposed to re-heat, therefore the touch surface of the PE material shall be cut-off (length of cut-off shall be subject to manufacturer recommendation), re-mill and repeat the jointing process.

Safety:

l   Do not approach the welding machine when welding in progress, do not touch the materials except trained workers

l   The heating plate is hot, do not touch or avoid contact with any material when idle

l   Maintain good ventilation

l   Aware of electric shock

l   Create a good communication including gesture for working

l   ventilate the workplace

l   Fire extinguisher must be in place when welding in progress, an urgent stop button for power supply shall be established

l   Safety induction to workers before works, and assign a person-in-charge to cover all the safety issue

Ivan Wong Sai Wing from Meinhardt