Reminder Letter for Installing Motor Purge to Increased-Safety Motor for Hydrogenation and Hydrogenation Production Unit Plants
Recently, incidents happened in several petrochemical companies in Shandong, Henan, Jiangsu due to the function failure, unit stop, or even motor explosion during the start-up and operation of increased-safety motor equipment for hydrogenation and hydrogenation production units (new hydrogen compressor, coal gas compressor, feed gas compressor pump etc.), which had led to adverse social impact and significant economic losses.
On the accident site, the investigator had found that all increased safety motors that were exploded were manufactured in accordance with GB3836.1,2,3,4-2000 version, which did not require motor purge prior to the start of increased safety high-voltage (6~10 kV) motor, and made preconditions that the prior motor purge should be conducted before starting the increased-safety power high-voltage motor. As the inherent defects complying with GB3836.1,2,3,4-2000, safety risks were hidden for the motor, which was the reason for explosion accidents.
For the increased-safety explosion-proof motor, the national standard had been upgraded to version GB3836.1,2,3,4-2010, in which GB3836 3-2010 clause 5.2.7 stated: "Motors should have special protective measures to ensure no explosive gas on the shell when starting. In accordance with the provisions of GB3836.1-2010, the motor operating instructions provided should include information on the implementation of supplementary measures, if required."(Note 1: supplementary measures included ventilation or fixed gas used in the motor housing examinations prior to motor start. Other methods provided by manufacturer, inspection agencies and consented by the users may be applied). It was suggested to add ventilation device for pre-start use to the same type of motor to increase safety.
We hereby reminded users that: check the motor manufacturing standard that used for hydrogenation and hydrogenation production unit. If it followed the GB3836.1,2,3,4-2000 for manufacturing increased-safety motor, it was recommended to modify the motor in accordance with GB3836.1, 2,3,4-2010 version, and add a positive pressure ventilation system for positive-pressure explosion-proof motor (applicable to the standby compressor) or add a pre-boot purge system for increased-safety motor (applicable to only one main compressor), so as to avoid motor accidents.
Anhui Huadong Chemical and Medical Engineering Co., Ltd. (“Huadong Engineering)
May 5, 2015