Yesterday, the US Chemical Safety and Hazard Investigation
Board (CSB) posted
a link
to their report
on the investigation of a 2021
acetic acid release
[removed from paywall] at the LyondellBasell La Porte
Complex in LaPorte, TX. The CSB reports that the inadvertent removal of
pressure retaining components of a plug valve caused the release of 164,000
pounds of high temperature (238˚F)
acetic acid mixture, killing two contract workers and injuring several others.
The Board identified two major safety issues and made six recommendations to
industry and technical organizations.

According to the CSB, contractor employees were working to
fix a leak on an in-service line in the acetic acid unit at the facility. During
that work they needed to remove the actuator from a plug valve on a pressurized
line. Instead of removing the bolts retaining the actuator unit, they loosened
the bolts holding the pressure-retaining valve components.

Citing similar incidents with plug valves, the CSB notes
that recurrence of these types of incidents points to the need to further
re-design plug valves so that it is more difficult to remove pressure-retaining
components while attempting to remove actuating equipment.  Additionally, the CSB reported that both the
company and the contractor considered the removal of the actuator a simple task
and did not provide the work crew with any sort of procedure or training and
did not adequately assess the potential risk of the operation prior to
commencing work.

The CSB made six recommendations to help prevent similar
incidents in the future:

LyondellBasell La Porte Complex – Update LyondellBasell policy documents to
require that procedures are developed for properly removing actuating equipment
from plug valves,

LyondellBasell La Porte Complex – Update LyondellBasell policy documents to require
that LyondellBasell competent employee(s) verify that contractors are
competent, adequately trained, and qualified to perform the required work,

Turn 2 Specialty Companies – Update Turn2 policy documents to require that
Turn2 employees are provided with written, detailed procedures for safely
conducting work on process equipment and are trained on the procedures before
the work is authorized to be performed,

American Society of Mechanical Engineers – Revise ASME Standard B16.34
Valves—Flanged, Threaded, and Welding End,

American Petroleum Institute – Revise API Standard 599 Metal Plug
Valves—Flanged, Threaded, and Welding Ends, and

Valve Manufactures Association of America – Work with ASME and API and develop
a white paper to the Valve Manufacturers Association of America addressing the issue
of plug valve design.

By admin