Type 631 replenishment tanker

The Type 631 tanker is a type of naval auxiliary ship currently in service with the People's Liberation Army Navy (PLAN).[1] Originally designed as a type that is capable of transport both water and oil, but only the oiler version entered service with PLAN.[1]

Class overview
Name:	Type 631
Operators:	People's Liberation Army Navy
Completed:	7
Active:	7
General characteristics
Displacement:	2,300 long tons (2,300 t)
Length:	60 m (196 ft 10 in)
Beam:	10 m (32 ft 10 in)
Draught:	3.3 m (10 ft 10 in)
Propulsion:	2 × marine diesel engines, 7,200 hp (5,369 kW) 2 shafts
Speed:	10 knots (19 km/h; 12 mph)
Complement:	30

Type 631 tankers in PLAN service are designated by a combination of two Chinese characters followed by three-digit number. The second Chinese character is You (油), meaning oil in Chinese, because these ships are classified as oilers. The first Chinese character denotes which fleet the ship is service with, with East (Dong, 东) for East Sea Fleet, North (Bei, 北) for North Sea Fleet, and South (Nan, 南) for South Sea Fleet. However, the pennant numbers may have changed due to the change of Chinese naval ships naming convention. Type 631 can be easily distinguished from other transport oilers by its transfer stations amid ship that enables it to carry out underway replenishment missions.[1] Another visual cue of this class is that from the bow to the midsection of the ship, there are three levels of freeboard, while all other Chinese tanker has a smooth curvy transition.[1]

Type	Pennant #	Status	Fleet
631	Bei -You 565	Active	North Sea Fleet
631	Dong -You 631	Active	East Sea Fleet
631	Dong-You 641	Active	East Sea Fleet
631	Nan-You 957	Active	South Sea Fleet
631	Nan-You 958	Active	South Sea Fleet
631	Nan-You 959	Active	South Sea Fleet
631	Nan-You 973	Active	South Sea Fleet

References

1. "Type 631 AOR". Retrieved 3 August 2015.