Blast and fire incident in close vicinity of product pipeline

INTRODUCTION

Title: Blast and fire incident in close vicinity of product pipeline.

Location: Blast in 22 KV HT Panel of Power Company near pipeline

Loss/ Outcome: 3.72 Kl product loss and loss of operation for 46 hours.

BRIEF OF INCIDENT

Fire took place due to blast of 22 KV HT Panel of a power company. Impact of blast & fire was such that there was damage to nearby structures and the road just in front of HT panel. One casualty was also reported of a local person who was present adjacent to the panel. Because of panel fire, HT cable got burnt and fire continued. There was an underground drain of municipality made of RCC chambers and HT cable was going inside drain. Product pipeline was also present parallel to RCC drain. During firefighting it was observed that fire was continuing intermittently in RCC drain.

As a precaution, shutdown of pipeline was taken and the section was depressurized and isolated by closing the sectionalizing valves. At the time of incident, product in the pipeline was Motor Spirit. The fire was doused with the help of foam fire tenders from organization, local administration and mutual aid partners. After defusing the fire, pipeline was inspected by excavating wherever fire was observed. During checking, a pilferage fitting with clamp, valve and piping was observed on the pipeline at 12 O' clock position. Gasket of the fitting was found in damaged condition causing leakage of product. After re-ensuring that fire was completely doused, the pilferage fitting was removed and repair was done with leak clamps.

OBSERVATIONS

1. The incident took place in populated area under location class 3 as per pipeline GIS data, population density index. The pipeline section where incident happened was recently re-routed for around 42 Km with additional protective measures were taken like providing higher wall thickness pipe of 12.7 mm as compared to normal thickness of 6.4 mm and providing extra soil cover.
2. It was observed that the miscreants had used drainage culvert of main road to enter near the pipeline. They have made a tunnel of around 2 meter long with diameter of around 2 feet. One valve was inside the chamber which was also found in closed condition. Clamp was having rubber padding on top side which was in torn condition.
3. The pipeline had following digital systems for monitoring;

1. SCADA : SCADA trends were analyzed and minor pressure drop confirmed between SV-2 and SV-3.
2. LDS: LDS system takes input from SCADA. Data continuity was found good. No leak alarm noted from for the location on or before the incident, might be because of very minor leak.
3. GPS: From 09:00 Hrs to 17:00 Hrs single line walker monitors the line. From 22:00 Hrs to 06:00 Hrs, 2 line walkers monitor the line. GPS trends on or before the incident were checked and were found okay.
4. PIDS: PIDS system was recently commissioned in the pipeline section. However, fine tuning of the system was pending and different activities like timing of different levels of alarm generation, operator acknowledgement time were under stabilization.

ROOT CAUSE OF INCIDENT

Blast incident in 22 KV HT panel of a power company in close vicinity of product pipeline coincided with the after effects of pilferage activity in the pipeline resulting into a major fire incident.

RECOMMENDATIONS

1. Enhancing awareness about Pipeline safety to other infrastructure agencies in the Pipeline route passing through populated area and other area where infrastructure development work is in progress.
2. PIDS system shall be modified for creation of specific event ID and different time stamps shall be made available. PIDS Alarm monitoring and closure process to be implemented & stabilized.
3. CP ON-OFF surveys, DCVG surveys should be conducted precisely and data to be analysed for identification of any coating damage due to pilferage activity.
4. In-Line Inspection of the newly laid pipeline section should be carried out within 2 years of commissioning to generate a baseline data and to identify any such external fittings.
5. Line walkers should be sensitized for thoroughly checking of culverts of similar nature along the pipeline route during line patrolling.