Inspection and verification

Post-weld heat treatment of a gas separator vessel

2015-06-18 10:16:25 | Lượt xem: 4092 | Inspection and verification

On 5 June 2015, ITVC Global performed post-weld heat treatment on a gas separator vessel manufactured at Dai Phat Equipment Co., Ltd. in Thai Nguyen.

This article records a gas separator vessel weld heat-treatment assignment using a heat-treatment machine with a CHINO JP controller and temperature recorder. The photographs and chart illustrate how the cycle was monitored for this job.

The parameters below apply to this assignment and are not a universal procedure for pressure vessels. The material, thickness, fabrication code and approved procedure determine the appropriate heat-treatment conditions.

Equipment used

Post-weld heat-treatment machine.
CHINO JP automatic programmable controller.
CHINO JP temperature recorder for monitoring temperature over time.

Cycle recorded for the assignment

Initial stage: ambient temperature to 300 °C; confirm the heating rate in the approved procedure.
Heat from 300 °C to 610 °C at 150 °C per hour.
Hold at 610 °C for one hour.
Cool to 210 °C at 90 °C per hour.
From 210 °C, allow natural cooling as described in the project record.

Photographs and temperature chart

Heat-treatment machine, controller and recorder at the site.

Resistance heater pads installed around the weld.

Thermal insulation and wiring during equipment installation.

Temperature controller used for the assignment.

Temperature chart for this assignment: heating at 150 °C/hour, holding at 610 °C for one hour, and cooling at 90 °C/hour during the specified stages.

According to TWI’s technical guidance, post-weld heat-treatment effectiveness depends on the material, temperature and holding time. Both heating and cooling need to be controlled to avoid adverse effects on the workpiece.

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