Before and after the 2017 blast in Manor Township, Lancaster County.

When the National Transportation Safety Board offered an initial explanation a month after a natural gas explosion that killed a UGI Utilities Inc. worker on July 2, 2017, in Lancaster County, it reported that a tapping tee coming off a two-inch main was leaking.

On Monday, while not attributing a cause to the accident that leveled a home, severely damaged two others, killed technician Richard Bouder and injured others, the NTSB instructed the device maker's parent company to improve its installation directions. It also told the federal Pipeline and Hazardous Materials Safety Administration to work with state pipeline regulators to make sure best practices are used to install such devices that connect gas mains to individual service lines that run to homes and businesses.

The Safety Recommendation Report did not have specific recommendations for UGI and it is not the board's final say on the matter. The investigation is continuing, the NTSB said.

And if you're into numbers, thousands of the PermaLink devices remain installed on UGI mains, the utility says.

Here are six things that can be learned from the 10-page NTSB document.

A single-family home exploded at 12:32 p.m. at 206 Springdale Lane in Manor Township. The residence had UGI natural gas service and after an odor was reported, the company responded and Bouder was working on the meter on the side of the home when the explosion happened, officials reported.

The main and service lines were removed after the blast and testing showed a PermaLock mechanical tapping tee was leaking at the connection to the main at the front of the home, the NTSB said. The device was installed in 1998 by UGI.

The safety board found that depending on what tools are used to install to the tee and what tolerances are used to tighten nylon bolts, the locking sleeve could fail to property attach and the bolts could eventually snap, causing a leak.

A PermaLock mechanical tapping tee.

2. What was UGI's role?

Following a federal regulation put in place in 2002, UGI "instituted a certificate program" for those who were to install the tapping tees. The effort included a written examination and a practical test, the NTSB said. But when the device was installed in 1998 in Lancaster County, "federal regulations ... did not exist and UGI did not have a training program for installing them. At the time, UGI was relying solely on the written installation instructions shipped with the tee assembly."

Those instructions did not, for example, dictate which wrench to use.

The installation requires the person adding the tee to be able to "feel ... the level of resistance ... in the wrench handles." Using 4.5-inch and 7-inch wrenches, the installer could "feel the following installation stages:

But using a 19-inch wrench, "changes in resistance were difficult to feel via the wrench handle." That wrench allowed the locking sleeve to be "easily driven below the stop, leading to an incorrectly installed locking sleeve and potential damage to the threads in the main," the NTSB said.

"Honeywell's written installation instructions, which were shipped with the third version of the PermaLock tee assembly, describe the general requirements for installation, but they do not specify all the necessary details to properly accomplish the installation and ensure that the locking sleeve attaches to the main," the NTSB said.

In the instruction video that was also produced, the device maker says shorter wrenches allow installers "to better sense resistance on the wrench handle" and "longer wrenches reduce the ability to sense the various installation phases," the NTSB said. But the directions don't say what size wrench to use, the NTSB said.

In the Lancaster County case, while "the cutter tool pierced a hole in the main, the locking sleeve did not progress down far enough into the tower to form threads in that hole. As a result, the locking sleeve was not attached to the hole."

The included "depth tube" "is also essential to correctly installing" the tee assembly, the NTSB said. The tube allows the installer to see how far the cutter assembly has traveled, helping to "verify the point at which the locking sleeve attaches to the main."

For correct installation, the instructions must "specify the exact tools... and that the depth tube must be used," the NTSB said. It said Honeywell should add those details to the instructions.

Honeywell didn't immediately respond to a request for comment.

4. What about the nylon bolts?

Two of the four nylon bolts on the tee assembly were broken in the Manor Township case due to slow crack growth, the NTSB said. That's likely the result of "varying tee assembly installation techniques," the NTSB said.

The locking sleeve is the "primary means of securing a PermaLock tee assembly tower to a main," according to a Honeywell representative, the NTSB said. But if it is not attached properly to the main, "additional tensile stress is placed on the four nylon bolts," which join the tower and the base around the outer part of the base, the NTSB said.

The bolts become the "fail-safe holding the tee assembly in place," the NTSB said.

If the sleeve is not properly attached, the bolts can "fracture," and that can be "sufficient to allow a gap to open in the saddle O-ring area between the tower and the main where gas can escape out of the tee assembly," the NTSB said.

The bolts are "susceptible to slow crack growth when over tightened," the NTSB added. A not-to-exceed torque limit for nylon bolts should be added to the assembly instructions and that number should be checked "and adjusted with a torque wrench immediately after installation," the NTSB said.

5. Are there any local examples?

After a natural gas leak on Aug. 5 of last year in front of at 2253 Firmstone St. in Wilson Borough, UGI provided the tee assembly to the NTSB to examine, the report said.

The locking sleeve was not attached to the main and two of the four nylon bolts were fractured, the NTSB said, adding it's not investigating the specific incident.

"The findings about the condition of the tee assembly are similar to those of the tee assembly involved in the (Manor Township) accident," the NTSB.

6. What has UGI done in creating a remediation program?

UGI has a program to repair or replace PermaLock tee assemblies, the report says. In its gas operations manual, it states that nylon bolts "are subject to breaking, and the locking sleeve may not have attached to the main during installation," the NTSB said.

UGI recommends replacing the nylon bolts, checking if the sleeve is attached to the main and dealing with leaks if they exist, the NTSB said.

If there are no leaks once the tee is excavated, the nylon bolts are replaced by stainless steel bolts, flat and lock washers and nuts, the NTSB said.

When a tee is leaking at the base, UGI cuts out that part of the main and replaces in with "a new approved tee assembly."

UGI stopped installing PermaLock tee assemblies about 10 years ago.

The utility and the NTSP differ on how many have been swapped out or fixed since 2007.

The NTSB said UGI has repaired or replaced 5,000 of them -- including 1,000 in the year since the explosion -- with "electrofusion tee assemblies," the NTSB said.

After UGI's gas division installed 19,000 of the plastic devices between 1997 and 2006, UGI spokesman Joe Swope said.

After a 2009 blast that killed one person and caused more than $1 million in damage, the Knoxville Utilities Board gas utility removed "all PermaLock tee assemblies from service throughout its distribution system," the NTSB said. That involved 1,875 devices bought and installed between 1997 and 2001, and the removal cost about $4 million, not counting employees' salaries and benefits.

After the Lancaster County explosion, UGI "instituted an accelerated gas leak survey" looking to find incorrectly installed PermaLink tee assemblies throughout its distribution system, the NTSB said. The company found 19 tee assemblies leaking as of June 12 and they were all associated with fractured nylon bolts, the NTSB said.

"UGI remains fully committed to the safe operation of its system, and to the safe and reliable delivery of energy to our customers and to the many communities we serve," Swope said in the news release.

Tony Rhodin may be reached at arhodin@lehighvalleylive.com. Follow him on Twitter @TonyRhodin. Find lehighvalleylive.com on Facebook.

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