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1. INSPECTION FINDINGS.
It is well know that engineering disasters are often the results of poor quality of workmanship and violation of construction rules.
2. The followings are the defects found on the fire water tank structure:
- Multiple tack welds / weld spatters.
- Multiple excessive grindings.
- Multiple Notches / Cracks like defects.
- Sharp weld edges / grinding Cuts on shell plates.
3. Tank inspection /Requirements.
- Pneumatic inspection of the reinforcement plates not done.
- Radiographic examination of Nozzles joint on tank NOT Done.
In section 3. 7.8.11 of API, the nozzle neck and transition piece... shall receive 100% RT.
- Plumbness check was NOT done and this is highly required to ensure that the internal equilibrium and stress level on the tank is not grossly affected (due deflection under service loading).
- Reports on tests- DP, RT MT were NOT submitted-they are required for evaluations and compliance certification.
4. Design issues
No design detail Calculations on tank component ports- such as
(i) Sizing of vent in accordance with AP1 standard 2000.
(ii) Shell opening reinforcement plates thickness i.e. Reinforcement pad/Area compensation calculations.
(iii) No design calculations for wind and seismic conditions- to check for overturning moment effects.
5. Construction practices / rules.
(i) LN used unqualified welders to do welding work on the tank at night.
(ii) And they also used uncertified welders to weld the shell nozzle flanges and piping spools. Due to these non-conformities; I gave LN the options to cut out the identified joints or to perform radiographic test to evaluate the quality of welds but none of the options was implemented till now.
(6) Documentation
(i) No Design calculation and approved drawing sets for the fire water tank.
(ii) No NDT procedures submitted,
(iii) No daily Quality reports submitted
(iv) Painting procedures submitted do not conform to Client's painting specifications.
(7) Contractor character
LN MD destroyed the working drawings for the fire water tank, and since then pooc inspectors have no drawings to inspect their job, and Such un-checked job is not acceptable.
(5) Recommendation:
i. LN should perform basic calculation or deploy conventional FINITE ELEMENT Analysis to predict the stresses which are then compared with the allowable value for a given fatigue life and probability of failure from the standards; by this, the tank could be qualified or deem acceptable, if every weld in it had a stress correspond to just below a 1% failure probability.
ii. LN should carry out dye penetrant test on all the grinded portion of the tank and arc strikes to check if there are cracks.
Note: None of the construction Codes accept crack defects because (from Linear Elastic Stress Calculations), it shows that stresses at crack tip are infinite and the material would fail under any load, no mater how small.
iii Ln should replace one of the fire water tank pumps. The coil of the pump got burnt by LN supervisor but instead of replacing with new pump, they are planning to re-wind the coil. This is not acceptable since the tank had not been commissioned. | 
Fabricated Fire Water Tank Qualification
Re: Fire water tank qualification
