NTSB Safety Recommendation P-15-035

NTSB safety recommendation P-15-035.

TO CONSOLIDATED EDISON COMPANY OF NEW YORK, INC.: Revise your plastic pipe fusion welding procedure to specify that the solidified beads should be visually examined after completing a joint to ensure the beads are uniformly shaped and sized around the joint as recommended in ASTM F2620, Standard Practice for Heat Fusion Joining of Polyethylene Pipe and Fittings.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 2015-06-29

Adopted Date: 2015-06-09

Overall Date Closed: 2015-12-21

Synopsis: On March 12, 2014, about 9:30 a.m. eastern daylight time, two adjacent multiuse five-story buildings were destroyed by a natural gas-fueled explosion and resulting fire. The buildings were situated on the west side of Park Avenue between East 116th Street and East117th Street in the East Harlem district of the Borough of Manhattan in New York City. The violent explosion damaged buildings on the east and west sides of Park Avenue and along East116th and East 117th Streets. The Metro-North Railroad suspended rail service for about 71/2 hours on the elevated railway along Park Avenue because of debris from the explosion on the track. Eight people died, more than 50 people were injured, and more than 100 families were displaced from their homes as a result of this accident. The cost to Consolidated Edison Company of New York, Inc. (ConEdison), of equipment damages, emergency response activities, remediation, and replacement exceeded $1.9 million.

Probable Cause: The National Transportation Safety Board determines that the probable cause of the accident was (1) the failure of the defective fusion joint at the service tee, installed by Consolidated Edison Company of New York, Inc., in 2011, that allowed natural gas to leak from the gas main and migrate into the building where it ignited and (2) a breach in the sewer line that went unrepaired by the New York City Department of Environmental Protection since at least 2006 that allowed groundwater and soil to flow into the sewer, resulting in a loss of support for the gas main, which caused the line to sag and overstressed the defective fusion joint.

Ntsbnumber: DCA14MP002

Report Number: PAR-15-01

Addressee Name: Consolidated Edison (Con Ed)

Addressee Status: Closed - Acceptable Action

Addressee Date Closed: 2015-12-21

Addressee Acronym: Con Ed

Addressee Organization Type: P-Private Industry

Communication Date: 2015-12-21

Communication Type: Official Correspondence

Communication Contents: We are pleased that you have amended the language in procedure G 8123-16 as follows: 4.2. After the heat fusion joints have cooled and solidified, the Operator Qualified installer and Operator Qualified peer inspector shall visually inspect all heat fusion joints around the entire circumference of the joint for uniformity and compare against the manufacturers’ recommended appearance guidelines. A) Butt fusion joints should have uniform double fusion beads rolled over to the surface, be uniformly rounded, and consistent in size all around the joint. The PE plastic pipe, tubing, and fittings must be properly aligned (NOT angled or mitered). The inspection requirements now included in revised G-8123 are consistent with those specified in ASTM F2620. Accordingly, Safety Recommendation P-15-35 is classified CLOSED—ACCEPTABLE ACTION.

Addressee Acronym: Con Ed

Addressee Organization Type: P-Private Industry

Communication Date: 2015-09-25

Communication Type: Official Correspondence

Communication Contents: -From Craig S. Ivey, President: We revised our heat fusion joining procedure, G-8123-16 to include additional language specifically stating that heat fusion joints shall be inspected after they have cooled and solidified to verify the beads are uniform around the circumference of the joint. We have previously trained our employees to inspect to this standard, but we elaborated on this detail in our procedure. The amended language in G-8123-16 is as follows (new language is highlighted in grey): 4.2 After the heat fusion joints have cooled and solidified, the Operator Qualified installer and Operator Qualified peer inspector shall visually inspect all heat fusion joints around the entire circumference of the joint for uniformity and compare against the manufacturers' recommended appearance guidelines. A) Butt fusion joints should have uniform double fusion beads rolled over to the surface, be uniformly rounded, and consistent in size all around the joint. The PE plastic pipe, tubing , and fittings must be properly aligned (NOT angled or mitered). The inspection requirements now included in revised G-8123 are consistent with the requirements specified in ASTM F2620, Standard Practice for Heat Fusion Joining of Polyethylene Pipe and Fittings.