Explosion of Liquid Nitrogen Sample Bomb

The incident took place inside a refinery while handling a sample bomb in which sample had been taken from a liquid nitrogen tanker. Prior to unloading the liquid nitrogen tanker, purity of nitrogen was to be checked. Accordingly, a sample had been collected. Subsequently, the sample bomb exploded during leak checking of the bomb valve and split into 02 pieces. One of the pieces (dome along with valve) penetrated in the upper part of left thigh of the truck cleaner/ helper. Truck helper succumbed to the injury a day later.

Recommendation -

1. Usage of non-standard sample collection devices:
Nitrogen Gas sample shall be taken instead of nitrogen liquid sample in line with the operating manual and standard practice. If liquid nitrogen sample is required, then appropriate collection device, suited for cryogenic services, is to be used.

2. Training:
Induction & refresher safety training shall be strengthened for all employees and contract workmen handling cryogenic product to improve awareness level. Toolbox talk, adequate training with coverage
to all possible hazards should be ensured to all concerned personnel.

3. Sample Collection Responsibility:
a) Responsibility of sample collection should be fixed and shall be done by the company designated persons who are trained and have the necessary skills to perform the task.
b) Purview of the contract labours/ drivers should be restricted to the job they are meant and skilled for.

4. Documentation:
a) Use of the sample bombs whose OEM documentations/ engineering design details are not available, shall be suspended.
b) OEM documentations/ engineering design details of equipment should be available as and when required.
c) Hydrotest records shall be maintained in standard format.

5. PPE:
Use of specialised cryogenic gloves while handling liquid nitrogen shall be ensured as per clause 8.1.8 of OISD-STD-155.

6. Other Recommendations:
a) Non-standard practices, like of testing of leakage of valve by dipping in flowerpot filled with garden water hose shall be brought to notice of concerned through reporting of unsafe act/condition and shall be discontinued.
b) In the event that laboratory reports that a sample bomb, used for the purpose for which it is meant, was received empty, the subject bomb usage should be discontinued immediately and the same should be sent for testing.
c) Tracking mechanism, like numbering of the sample bombs, should be followed religiously so that it can be known at any time that how many times the bomb has been used.
d) Company should take non-conformity to procedures mentioned in operating manual, improper usage of equipment for which the same is not meant/ designed, & inadequate supervision, seriously
and take necessary corrective actions for improvement.

Source : https://www.oisd.gov.in/