1. Optimization of Interface Quality in Hot Melt Welding
Hot melt welding interface is prone to the following problems: asymmetric curl, excessive dislocation, bubbles and pits on the weld surface and other quality problems.
Cause analysis:
(1) Different specifications of welded pipes;
(2) Semi automatic welding machine is used, and welding is not carried out according to the specified welding parameters. For example, the driving pressure of the welding machine is too high, and the cooling time is too short;
(3) The performance of automatic welding machine is unqualified;
(4) The parameter setting of the hot-melt welder is inconsistent with the pipe performance (the performance (such as thermal stability) of PE pipes produced by different manufacturers is different)
(5) Construction in wet and other adverse weather conditions;
(6) The specified hot melt fixture and roller bracket were not used during welding, and the quality of butt joint did not meet the requirements;
(7) The welding machine operator has not received professional training and has no certificate.
2. Optimization of welding quality of electric fusion joint
Electric fusion welding is the welding method that is least affected by the external environment.
The interface of electrothermal fusion welding is prone to the following problems: mainly "false welding".
Cause analysis:
(1) When connecting PE pipes, do not use special clamps to keep the two PE pipe interfaces "concentric", and force assembly to cause uneven interface clearance and reduce the welding area of the interface;
(2) There is a compatibility issue between pipes and accessories. Fittings and PE pipes do not belong to the same manufacturer.
(3) The oxide layer is scratched unevenly or scratched unevenly, causing the end of PE pipe to be out of round, the interface gap to be uneven, and false welding;
(4) Move the connector during connection;
(5) The welding cooling process shall not be carried out under natural conditions, and water cooling or forced air cooling shall be adopted;
(6) If the length of the pipe inserted into the electrofusion pipe is insufficient, it may lead to desoldering.
3. Optimize the quality of polyethylene pipes and fittings
PE pipes and pipe fittings are prone to the following problems:
As we all know, PE is a very common polymer material in life, and plastic bags for shopping are made of PE plastic.
Compared with metal pipes, PE pipes have obvious advantages, excellent physical properties, non-toxic pipes, and good impact and stress cracking resistance. PE pipes can be divided into three types: PE mine pipes, PE sewage pipes and PE water supply pipes.
Such problems are generally caused by non-standard operation during transportation and construction
The reasons are as follows:
(1) The pipeline is not backfilled timely as required after excavation, and has been covered and soaked by construction waste and rainwater for a long time, affecting the safety and service life of the pipeline;
(2) The pipeline is damaged due to non-standard operation, dragging and throwing of PE pipes during transportation, loading and unloading, and storage;
(3) No roller support was used during construction, resulting in scratches on PE pipe wall;
(4) Pipeline laying problem: the pipeline stored on site has not taken sunscreen and rainproof measures, which affects the pipeline performance and shortens the service life of the pipeline;
(5) The quality of pipes and fittings does not meet the requirements or expired pipes and fittings are used.
4. Other optimization directions
(1) Warning tape is not laid for pipeline backfilling as required, and the trench depth is not up to standard;
(2) If the polyethylene pipeline is not backfilled with yellow sand and fine soil as required, and the pressure pipeline surface is covered with stones or sharp objects, it is easy to leak air at the interface, which seriously threatens the safe operation of the pipeline in the future;
(3) If the pipe orifice is not blocked after the pipeline construction is interrupted or there is water and soil during the construction backfilling, a large amount of impurities and rainwater may be left in the pipeline, affecting the safe and stable operation of the pipeline in the future.
