Change the steam purging pressure of the pipeline
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Dear colleagues: In the past, the steam purging ports on our company’s pipelines and equipment were connected to low-pressure steam (3.5 kg, 177 degrees Celsius). The production department pointed out that using low-pressure steam for purging the pipelines and equipment during shutdowns for maintenance is too slow; in order to reduce the purging time, they proposed using medium-pressure steam (17.6 kg, 260 degrees Celsius) instead. My question is, colleagues, is this approach appropriate? What are the risks?
Hello. This is not the right question. It’s a matter of pipeline specifications. And the voltage tolerance issue. The pressure increases by 5 times. It’s best to make a PHA
When temperature and pressure increase, there is a risk of deformation and displacement of the pipe supports; it doesn’t seem feasible. In the steam purging operations I’ve been involved in, pressures below 10 kilograms were used.
It should be possible as long as the following conditions are met simultaneously: 1. The design temperature of the equipment and piping systems is ≥260°C, and the design pressure is ≥1.8 MPa； 2. The nominal pressure of the fittings (flanges, valves, etc.) in this system is capable of withstanding a pressure of ≥1.8 MPa at 260°C (this can be determined using the temperature-pressure charts for flanges and valves) ； 3. The pipe systems (pipes, fittings, pipe supports/hangers) and the pipe ends of equipment must meet the requirements of flexible design (stress verification calculations can be carried out). For your reference
Thermal purging must be handled with care. Firstly, there is the issue of increased pipe pressure – it’s not just a matter of a five-fold increase, but also the temperature coefficient comes into play. Secondly, there’s the issue of pipe flexibility, that is, expansion; calculations are necessary for this. Moreover, the pressure has already been increased too much in your case
I am also concerned about the thermal displacement of the pipes during purging. Thank you.
Personally, I think making changes rashly is inappropriate; a HAZOP STUDY should be conducted before making any changes. Thank you, moderator.