In 1920 Anglo-Saxon Petroleum Co., a wholly-owned subsidiary of the Royal Dutch Shell Company, decided to expand their oil carrying fleet by placing orders with a number of United States West Coast shipyards. In August 1920 it was reported that one such order for three tankers of approximately 8,400 deadweight tonnage each was entered with the Southwestern Shipbuilding & Drydock Co.[3]
Silvanus was the second of these three vessels (the other two being SS Scopas and SS Semiramis), and had her keel laid at the shipbuilder's yard on 20 October 1920, and launched on 30 June 1921, with Mrs. Earl L. Miller, wife of the Pacific coast manager of the Royal Dutch Shell, being the sponsor.[4] The tanker was built on the Isherwood principle of longitudinal framing providing extra strength to the body of the vessel. The vessel was built according to blueprints provided by the Anglo-Saxon Petroleum Co., had two decks and was constructed on the three-island principle. The tanker had a cargo pump room located amidships and was able to carry up to 60,000 barrels of oil. The vessel had her machinery situated aft, was equipped with wireless apparatus and had electric lights installed along the decks.
As built, the ship was 412feet long (between perpendiculars) and 53.3feet abeam, and had a depth of 31.2feet.[5] Silvanus was assessed at and and had deadweight tonnage of approximately 8,400.[5] The vessel had a steel hull and a single 556 nhp triple-expansion steam engine, with cylinders of 27inches, 45inches and 74inches diameter with a 48inches stroke, that drove a single screw propeller, and moved the ship at up to 11kn.[5] The steam for the engine was supplied by three single-ended Scotch marine boilers fitted for oil fuel.
After successful completion of sea trials on August 9, the tanker was delivered to Dutch Shell representatives the next day and put under control of Nederlandsch-Indische Tankstoomboot Maatschappij, a wholly-owned subsidiary of the Royal Dutch Shell, which controlled and operated the company's vessels in the East Indies.
After the tanker was delivered, she remained in San Pedro for the next two weeks, before sailing out for loading at San Francisco. She reached her destination on August 28, and immediately proceeded to Martinez to load full cargo of kerosene for delivery to China.[6] Upon undergoing her final inspection, and loading the cargo, Silvanus departed San Francisco on August 31, bound for Shanghai.[7] After an uneventful voyage, the ship reached Tianjin on October 1.[8] The tanker then proceeded to visit ports of Shanghai, Singapore and Balikpapan, and returned to San Francisco on December 12 via Victoria and Seattle, thus successfully completing her maiden voyage.[9] She then sailed from San Francisco on December 24 for Shanghai to commence her service in East Asia.[10] The tanker reached her destination at the end of January and immediately proceeded to Australia via Singapore, arriving at Melbourne on 10 March 1922.[11] After discharging her cargo, the tanker departed on March 14 for Balikpapan, the major oil producing center in the Dutch East Indies.[12] From there Silvanus departed with a full cargo of oil on April 4, and arrived at Thames Haven on May 13.[13] Subsequently, Silvanus spent the remainder of 1922 transporting fuel oil between Abadan and Suez, before departing in early January 1923 back to Singapore and Balikpapan. From there, she again sailed for Australia, arriving at Adelaide on 21 February 1923 with a cargo of oil, kerosene and motor spirit.[14] The ship then went back to Balikpapan and from there sailed out for Thames Haven, reaching it on May 7.[15] She subsequently sailed out for Port Arthur where she loaded oil and departed on June 3 bound for Indian ports.[16] The tanker reached Bombay on July 15 via the Suez Canal.[17]