Trans Mountain revises heavy crude standards on pipeline after quality concerns

By Arathy Somasekhar

HOUSTON (Reuters) - Canadian government-owned oil pipeline operator Trans Mountain last week revised standards for accepting crude oil on its recently expanded system after buyers raised concerns about the crude oil arriving on the line, a regulatory filing showed.

The U.S. West Coast refining market is expected to be a major outlet for the Canadian heavy oil shipped via the Trans Mountain pipeline expansion, called TMX. But 10 companies and refiners including Chevron and Valero Energy told a pipeline regulator the line's crude quality specifications could deter their purchases.

Trans Mountain last week said it would replace the existing pool of "Low TAN (Total acid number) Dilbit" with a pool of "Pacific Cold Lake," or bitumen diluted with crude having a density of less than 800 kilograms per cubic meter.

Pacific Cold Lake's and Pacific Dilbit's acidity will be limited to a maximum of 1.1 milligrams of potassium hydroxide (KOH) per gram, compared with an earlier limit of 1.3 mg KOH/g, the filing showed. High levels of acidity can corrode processing equipment and cause damage.

Trans Mountain also defined vapor pressure limits for its Pacific Cold Lake, Pacific Dilbit and Synthetic Bitumen crude pools, as less than or equal to 70 kilopascal (kPA) between May 1 and Nov. 30, and less than or equal to 76 kPa between Dec. 1 and April 30. High pressures cause more vapors to leak from tanks into the atmosphere.

"Based on the consultations (with shippers), Trans Mountain is proposing changes to the heavy Crude Petroleum pool specifications," the company wrote in its regulatory filing. Trans Mountain added it will continue to engage with its shippers regarding changes to the light crude petroleum pools.

"At this time, Trans Mountain is not aware of any Shipper that intends to oppose the revisions that Trans Mountain is making to the heavy crude pools in the Service Standards, the company also noted.

(Reporting by Arathy Somasekhar in Houston and Nia Williams in British Columbia; Editing by Josie Kao)