Safety Technology Exchange Edition: Daily Question (April 24, 2016) – Extra points available for this issue
Thread Content
Type: Discussion question. Topic: [Safety Technology] When starting up a chemical plant, it is necessary to ensure airtightness to prevent material leakage; nitrogen purging is required to avoid explosions. When shutting down the plant, purging is also necessary to ensure safety during operations. I have yet to find any standards regarding the specific parameters for these operations, and the approval plans often include inconsistent specifications. As far as I know, the requirements are as follows: The standard for airtightness is a leakage rate of ≤0.4%. The standard for nitrogen purging is an oxygen content of <0.2% (V/V). The standard for working in a shutdown state is a flammable gas content of <0.5%. Could everyone please explain these standards and regulations? This issue focuses mainly on discussions; additional points will be given for those who can provide references in accordance with the guidelines. Everyone is welcome to participate!
Air-tightness acceptance criterion: Pressure drop ≤ 0.015 Mpa/h. Nitrogen purging acceptance criterion: Oxygen content < 0.5% (V/V). Acceptance criterion for working with fire during shutdown: Flammable gas content < 0.2%
An oxygen content of less than 0.5% is considered acceptable
1. For the airtightness test of the system, it is specified that the pressure should be maintained for 24 hours; for the airtightness test of individual units, the pressure needs to be maintained for 8 hours. The passing criterion for this airtightness test is an average leakage rate of ≤0.25% per hour. 2. The acceptable standard for nitrogen purging is an oxygen content of <0.2% (V/V). 3. The acceptable standard for working on the equipment during shutdowns is a flammable gas content of <0.5%
Before starting operations, airtightness must be ensured to prevent material leakage; nitrogen purging is necessary to avoid explosions. When shutting down operations, the cooking vessel must be purged to ensure safety during work
Air-tightness acceptance standard: Leakage rate ≤ 0.4%. Nitrogen purging acceptance standard: Oxygen content < 0.2% (V/V). Acceptance standard for working with fire during shutdown: Flammable gas content < 0.5%
I hope the original poster can share the results of the discussion, so we can learn from it too!