Impacts of TETCO's Natural Gas Pipeline Explosion

TETCO Natural Gas Pipeline
Blog May 03, 2016

A massive explosion occurred Friday on TETCO’s Penn-Jersey Line in the M3 zone. The explosion occurred on one of its 30” lines near Salem Township in Westmoreland County, PA, about 40 miles east of Pittsburgh. Flows beginning at the Delmont compressor (the western boundary of the M3 zone) have been cut to zero, and the flow impacts radiate eastward from Delmont.  Based on the timeline of similar large diameter pipeline explosions in the past, Genscape believes repairs are likely to take between 5-15 days, but clearly it could take longer.  

The initial impact on flows is significant (see Genscape's Natural Gas Real-Time (RT) TETCO flow map below). On April 28, just prior to the explosion, flows through Delmont were around 1.3 BCF/D relative to 2.6 BCF of capacity (~50 percent utilization). Flows through Delmont were shut off immediately after and averaged 1.07 Bcf/d in the five days prior (including a peak of 1.36 Bcf/d on gas day April 27). On Saturday, April 30 and Sunday, May 1, TETCO did report backward flows through Delmont of about 180 MMcf/d, though none for today. All compressors east of Delmont and west of Perulack registered similar declines. 

TETCO flow map for Delmont explosion

On Monday, May 2, TETCO M3 Deliveries cash basis closed near a three-week high at ($0.25), up from last Thursday’s ($0.62), while TETCO M3 Receipts dropped $0.02.  Algonquin Citygate picked up $0.21 from Thursday’s close to finish Monday at $0.64.

TETCO quickly posted notice April 29 that two production meters would have to be shut in. Those two points had been producing about 250 MMcf/d prior to the event.

TETCO has also been compensating by reducing its deliveries to interstate interconnects. The largest declines are in deliveries to Algonquin at Lambertville have been averaging 142 MMcf/d since the explosion, versus 373 MMcf/d in the five-days prior to the explosion; and deliveries to Dominion at Perulack, down to 31 MMcf/d versus 140 MMcf/d.

Flows east of Perulack – where TETCO’s Leidy Line connects to the Penn-Jersey northern line – are also down, though less so. TETCO increased volumes flowing southward on Leidy by increasing its storage withdraws from about 100 MMcf/d up to about 650 MMcf/d.

Deliveries to power plants so far appear relatively unaffected. There are six major power consumers captive to the system that collectively had been consuming roughly 550 MMcf/d. The largest is the PPL Martins Creek plant (177 MMcf/d), Genon/Reliant Hunterstown-Adams (~120 MMcf/d), and PPL JP Morgan plant (116 MMcf/d).

Farther east flows are less affected. Flows east of the merge point of the northern and southern lines are also unaffected. This appears to be a product of the aforementioned factors, combined within increased flows along the southern line. The southern line has more production tied into it. That is being used to increase flows through the Bedford compressor, where flows are up into the 200 MMcf/d range after running around 155 MMcf/d last week.

It is uncertain how long the system will be down and/or affected, but Genscape has reason to believe it will not be more than a week or two. First of all, there are parallel lines adjacent to the ruptured one that may be able to come back into service soon. Second: similar events on other pipelines in the US and Canada have taken just a few days to repair.

The section of TETCO where the explosion occurred features four lines running in parallel: a 36” line, two 30” lines, and a 24” line. While there has not been confirmation the other lines have been damaged, TETCO has shut them down as a precautionary measure. It is possible these lines may be brought back into service before repairs on the ruptured line are made. If that is the case, the remaining lines should have enough flow capacity to satisfy downstream obligations based on recent nomination levels. Similar events on other pipelines have been repaired rather quickly. In January, the REX pipeline ruptured; flows were restored within about 12 days. Last June, a 42” Energy Transfer line near Cuero, TX exploded was returned to operation in three days. In 2014, a rupture on Viking’s 24” mainline took 3 days to fix. And in 2011, a rupture on Bison’s 30” line took about 15 days to repair. A system-wide OFO for all deliveries into the system is in effect, and an OFO for all deliveries and receipts in the M2 zone is also in effect.

How long will the repairs take?

There have been a number of large diameter pipeline explosions over the years. The amount of time it takes to repair a large diameter pipeline ruptures are usually a matter of days (not weeks). Below are three examples of large diameter explosions that were repaired in 3, 11, and 15 days respectively, but clearly repairs can take longer. 1-2 weeks to repair the line(s) from the initial event is our best guess.

The Texas Railroad Commission (RRC) says the explosion of a 42″ natural gas pipeline near the town of Cuero, Texas in June 2015 was caused by a “material failure” on part of the pipeline. Energy Transfer operates the pipeline that exploded on June 14, 2015. The company is planning to build two pipelines of the same size in West Texas – the Trans-Pecos Pipeline and the Comanche Trail Pipeline. The RRC regulates the oil and gas industry and investigated the Cuero explosion shortly after it happened. A 46-page report on the explosion obtained by Marfa Public Radio says the pipeline ruptured because of an “excessive bending load” – essentially too much tension on part of the line – which led to a crack that started at the weld and moved from the bottom up. Nobody was hurt in the blast, but 16 people were evacuated. Witnesses reported seeing flames shooting about 100 feet up into the air.  The part of the line that exploded was shut off and isolated, but according to the RRC’s report, it was repaired and back in operation about three days after the explosion.

 

Pipeline explosion comparison

On January 29, near Bowling Green, Missouri, a rupture in a Rockies Express 42-inch natural gas pipeline blew a 20 by 20-foot crater and forced a six-hour evacuation of 50 families. The rupture occurred in a vacant field a few yards east of Pike County Road 43. Strong winds helped dissipate gas until a temporary cap was put in place. Update: Tallgrass Energy’s 1.8 Bcf/d Rockies Express Mainline Segment 300 Returns to Service in Missouri February 9; Force Majeure Remains in Place According to flow data on Tallgrass Energy’s informational postings website, natural gas flows on Segment 300 of the company’s Rockies Express (REX) Pipeline resumed at low levels February 9. On February 10 and 11, the segment returned to normal rates of approximately 1.3 Bcf/d. However, according a critical notice posted to the website, the Force Majeure on Segment 300 remains in place. Tallgrass Energy on January 29 reported that Segment 300 experienced an operational interruption due to the rupture near Bowling Green in Pike County, Missouri

On July 20, a six-month-old, 30-inch natural gas pipeline exploded near Gillette, Wyoming, creating a 60-foot (18 m) crater. There was no fire, nor any injuries. Construction or installation issues caused the failure.

Update May 5, 2016 12:40PM ET

While the return of all four lines may take longer than the 1-2 weeks Genscape initially estimated, it appears that at least partial capacity through Delmont is likely to be restored next week (per TETCO’s latest notice). PSHMA issued a corrective action order yesterday (summary below). Corrosion at a weld is the likely culprit, although a final determination has not been made. Corrosion has been the cause of many of the 77 explosions involving gas infrastructure (mostly pipelines) in the last 10 years. 

There is a chance that TETCO is required to operate at reduced pressure after the repairs are completed. If PHSMA requires a 20 percent reduction in pressure then capacity could be reduced by up to 20 percent and capacity through Delmont would be permanently reduced from 2.6 BCF/D to around ~2.1 BCF/D. Genscape does not know if a pressure reduction will be required.

Brief summary of PHMSA’s corrective action order:

The cause of the failure has not been fully determined, the preliminary investigation identified evidence of corrosion along two circumferential welds: one at the point of failure and another that was excavated. The pattern of corrosion suggests a possible flaw in the coating material applied to the girth weld joints following construction welding procedures at the time. TETCO must expose the ruptured line for at least two girth welds on either side of the ruptured site to examine for corrosion, coating condition or other damage. If damage is discovered then more pipe must be exposed until at least 10 feet  of undamaged pipe is exposed and examined. TETCO must repair or replace pipe or coating where necessary. The other lines must also be exposed at least to girth welds in both directions from the point of failure and undergo the same process as the ruptured line. Restarting procedures for each line will involve pressure increments of 25 percent, 50 percent, and 80 percent held for one hour. After reaching 80 percent, TETCO must receive written permission for each line before increasing to final normal operating pressure.

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