GhubrahIncidentInves.. - authority for electricity regulation, oman

Report Number: R 8991
Issue: 1.1
2 FINDINGS
On arrival at site, Senior Sogex personnel (including the site General Manager) were
interviewed to determine the circumstances and the probable root cause of the
incident. Work permits, work orders, procedures, evidence of competencies and
health and safety documents were requested and received. The author received full
and open co-operation from Sogex personnel throughout the investigation.
On the 25/03/06, a Limitation-of-Access (LOA) Permit-To-Work (PTW), LOA
No.10795/L was issued to carry out routine maintenance on the external surfaces of
the Phase 3 Hypochlorite Storage Tanks, C and D (See Appendix A). The permit
was issued for (1) cleaning, (2) surface preparation and (3) painting. The cylinders
were to be left in service and the permit clearly states that no isolations were to be
carried out and that the civil department (conducting the painting operation) were to
take all safety precautions. In this respect this specific PTW/LOA covered activity of
a ‘cold’ work nature, although it is observed that the relevant section of the permit
designed to indicate ‘hot’ or ‘cold’ status was left unspecified.
On inspection of the job site on cylinder ‘D’, the civil department reported that the
cylinder jacket was badly corroded and hence a work order (Reference No. LO
42/04/06) was raised on 05/04/06 to the Mechanical Department, to replace the
cladding (hood) on cylinders A, B, and D (See Appendix B). The work order No. LO
42/04/06 references PTW/LOA No. 10795/L.
Evidence was requested regarding the competency and authorisation of the permit
issuer and work order issuer. Sogex personnel produced relevant CVs and
authorisation memos stating that the persons concerned had been assessed and
found competent to sign permits (see Appendix C).
The work to replace the cladding involved the removal of the corroded cladding and
the fabrication and installation of replacement cladding. To replace the cladding it is
necessary to use drills for the riveting process.
It appears that the mechanical fitters were left to complete the work with no periodic
site inspections by the management and no safety departmental presence.
Work on the ‘C’ Hypochlorite cylinder had been performed under a separate internal
work order (LO 37/03/06, not included in this report), without incident. However,
during the process of installing the newly fabricated hooding of the ‘D’ cylinder, an
explosion occurred resulting in a ‘fire ball’ that fatally injured the two Sogex
maintenance fitters involved. They reportedly were able to climb down from the top
of the cylinder, a difficult feat, to seek assistance.
Once the incident had been discovered, the Hypochlorite plant was shut down and
the two employees were immediately transferred to hospital where they were placed
in intensive care, but subsequently passed away.
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