DIAMOND POINT — A business conducting “explosive welding” on property west of Port Angeles says it might have been a source of the loud booms that rattled west Port Angeles and Joyce residents recently.

But other booms felt elsewhere on the North Olympic Peninsula remain mysterious.

Joe Munn, operations manager of Souriau PA&E Bonded Metals Division at 2249 Diamond Point Road, said his company has been doing such welding west of Port Angeles.

A series of booms heard last Thursday morning were part of his company’s operations, Munn said.

“It is loud. It has to be loud,” he said.

He added that the 45-year-old company was well-known as a producer of loud explosions in the past.

“When Mount St. Helens blew up, people thought it was us,” he said.

Munn said the company always is working to reduce its noise levels, timing explosions to take place when atmospheric conditions reduce the chance of the shock wave being “bounced” into other areas.

He said temperature inversions, fog and sometimes a single cloud over the Strait of Juan de Fuca can keep the shock wave moving past the usual sound wave range, sometimes as far as Sooke, B.C., on the north side of the Strait.

Since 1970, the company has used explosive welding to bond dissimilar metals.

The explosion cleans the surface, Munn said, then creates the heat and pressure that bonds metals together in a weld that is as strong as the weaker metal used.

Some metals are incompatible for explosive welding, so a third metal is sandwiched between the two metals for a successful bonding.

“It can take 20 to 40 hours of labor to prepare an assembly to bond metals together, depending on the metals, size and complexity,” Munn said.

While the company’s base is 10 miles northeast of Sequim, Munn said a property west of Joyce is used for the explosive welding because of the amount of noise generated by the process.

He said the company holds a collection of permits for the use of explosives from the county, state and federal agencies; has signs, air horns and blocked roads to warn away anyone who may be in the woods; and monitors decibels and ground vibrations at the blast site.

“[In 45 years], no one has ever gotten hurt,” he said.

Munn said about 80 percent of the company’s products are for defense industries, producing parts for Navy ships and aerospace.

The company’s products range from specialized rocket nozzles for Space X and other rocket manufacturers to simple but durable piping transitions for ships and tie-downs for aircraft on aluminum ship decks, he said.

Although there are only four companies in the U.S. that perform explosive welding, two of them are in Clallam County.

The other company may be responsible for other booms heard in the county, Munn said.

High Energy Metals Inc., 293 Business Park Loop in Carlsborg, also performs its explosives work on the West End.

However, its explosive range is located southwest of Lake Crescent and not in an area where the sound would likely travel to residential areas, said Dave Brasher, a co-owner of the company.

“It’s mainly loggers and Forest Service folks,” he said.

Brasher said that when he heard about the most recent mystery booms, he checked his business’ schedule and found that the booms Feb. 25 and March 11 did not match his company’s activities.

So some of the booms remain a mystery, continuing the tradition of unexplained noise and shaking on the North Olympic Peninsula.

What about the other mystery booms?

The U.S. Geological Survey has said its instruments show the booms originating from the air, not the ground.

The Navy has denied any sonic booms caused by aircraft from Naval Air Station Whidbey Island.

Spokespeople for other military units in the region have said they have had no activity in the Strait during the times the booms were heard.

Those include Canadian Forces Base Esquimalt, which operates a demolition range on Bentinck Island northwest of Port Angeles on the Canadian side of the Strait, and Joint Base Lewis-McChord near Tacoma, which provides a demolition team for military training ordnance that occasionally washes up on beaches.

Booms — both explained and unexplained — have been heard in the North Olympic Peninsula for decades.

A series of booms Port Angeles in 1982 was found to be from Navy exercises in the Strait.

Unexplained booms were reported in Port Angeles in 2006, and in 2007, booms were heard in the Dungeness Valley, with houses shaken and a report of at least one broken window.

Port Angeles residents were again shaken by unexplained, loud booms in 2009.

In 2011, a series of reported booms was identified by the Weather Service as thunder.

A series of after-dark booms in 2012 was found to have been caused by an air cannon set up by farmers in the Sequim area to scare away opportunistic birds from freshly planted fields.

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Reporter Arwyn Rice can be reached at 360-452-2345, ext. 5070, or at arice@peninsuladailynews.com.