DISCLAIMER

HSE Risk Management Services Private Limited accepts no liability or responsibility whatsoever for it in respect of any use of or reliance upon this Methodology by any third party.

Copying this Methodology without the permission of HSE Risk Management Services Private Limited is not permitted.

1.     Proposed Methodology

1.1. Introduction

Nitrogen inertization, also known as nitrogen purging or blanketing, is a process used to protect products and processes from the harmful effects of oxygen and moisture. This technique involves displacing oxygen and moisture with nitrogen gas, which is inert, meaning it does not react with other substances under normal conditions. The concept is widely applied in various industries to ensure safety.

1.2. Methodology

·        VALIDATION PROCEDURE FOR N2 INERTIZATION

N2 inertization is required in 3 steps

I.     N2 inertization in vessel before transferring/charging of 1st flammable chemical.

II.    N2 inertization in vessel during the process (reaction/unit operation) in the vessel.

III.   N2 inertization in vessel during empty out.

·        Validation Procedure No. “A”:  N2 inertization in vessel before transferring/charging of 1st flammable chemical.

1.      Volume of N2 required for inerting the vessel before transferring/charging of 1st flammable chemical is provided in ‘Design validation’ under ‘Annexure-1’.(Refer Column-G)

2.      Flow rate of nitrogen to vessel should be fixed through orifice of appropriate size. Flowrate can be measured through a flowmeter installed in N2 line to equipment.

3.      Formula for Time required for nitrogen inertization in the equipment =  (Volume of reactor/Flowrate of nitrogen)

4.      Provide nitrogen flow to vessel for the time calculated as per step 3. 

5.      Measure the oxygen level at the bottom of reactor.(1st cycle)

6.      If the oxygen concentration is above required LOC, repeat the 4th step and measure the oxygen concentration at the bottom of reactor till the oxygen level reaches equal to or below required LOC. (2nd and 3rd Cycle)

7.      Initially, validate no. of cycles needed of inerting in Step 6.

8.      Perform Step 4 to 7 three times.

9.      Frequency of validation should be every in a six month or if there is any major maintenance of equipment/vessel entries/maintenance of connected piping/dish-ends/valves etc to equipment.

·        Validation Procedure No. “B”:  N2 inertization in vessel during the process.

1.      Once the vessel is inertized as per Validation Procedure No. A,  keep the vessel inertized with the help of nitrogen at a pressure 100mm water column above the operating pressure. 

2.      After every 1 hour, record the Oxygen level at the bottom of vessel for upto 3 hours.

3.      If oxygen level is above LOC, increase the pressure to 200mm water column and record the Oxygen level at the bottom of vessel after every 1 hour, for upto 3 hours. Increase the pressure by 100mm water column untill two subsequent oxygen level reading are below required LOC.

4.      Frequency of validation should be every in a six month or if there is any major maintenance of equipment/vessel entries/maintenance of connected piping/dish-ends/valves etc to equipment.

·        Validation Procedure No. “C”:  N2 inertization in vessel during empty out 

1.      After completion of Validation procedure, A and B , fill the reactor with water and empty out the vessel as per SOP of equipment (pump/gravity/vaccum etc) while keeping the nitrogen supply open through the orifice.

2.      Calculate the flow of N2 required during the empty out the reactor by formula = (Volume of reactor/time required for completely empty the vessel)

3.      Measure the oxygen level at the bottom of vessel after empty out. The oxygen level should be below the required LOC.

4.      If oxygen level is above LOC, increase the flow of nitrogen by 5% and measure the oxygen level at the bottom of vessel after empty out. 

5.      Perform steps 1-4 on a test vessel 3 times to validate the process.

6.      This process shall be reviewed once in a six month or if there is any major maintenance of equipment/vessel entries/maintenance of connected piping/dish-ends/valves etc to equipment

1.3. Guideline Used for N2 Inertization and Validation  

·       NFPA-69

1.4. Data Requirement

Ø  Equipment P&IDs

Ø  SOPs

Ø  MSDS of Chemicals

Ø  Nitrogen upstream Details and Nitrogen Purity Level

Ø  Batch Quantities of material charged 

1.5. Project Deliverables

Table 1: N2 Inertization and Validation Study

1.6. Software to be used

·        The N2 Inertization and Validation calculation is done using Microsoft Excel.