The company, a wooden post manufacturer, faces $109,548 in proposed penalties.
An investigation by the Health and Safety Executive into the incident found that the company had not implemented procedures to ensure machinery was isolated before starting maintenance work.
OSHA investigators concluded flammable vapors or gases from a vacuum truck leaked, igniting the pipeline.
OSHA cited the manufacturer of dog treats for 19 violations, including failing to implement lockout/tagout procedures, blocking electrical panels, failing to develop a hazard communication program, and exposing workers to confined space, machine guarding, and electrical hazards.
During the Puyallup event, which will run from 7 a.m. to 3:45 p.m., speakers will cover topics including fall protection, trenching, biohazards, lockout/tagout, and silica exposure prevention.
Cal/OSHA cited Alhambra Foundry for similar violations eight years ago.