Sulphur Systems - Sulphur Piping
September 8, 2010

Introduction Piping Valves Service Conditions         Molten Sulphur         Steam Jacket Gaskets Steam Jumpers

Associated Links Sulphur Properties Sulphur Safety Sulphur Melting Sulphur Filtration Sulphur Storage Sulphur Furnace Procedures

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Introduction

It is a design and operating challenge to move molten sulphur around a plant.  To keep the sulphur molten and pumpable at the proper viscosity, all piping and equipment handling molten sulphur must be heated and insulated.   Steam jacketed piping is by far the most common way of conveying molten sulphur throughout the plant.  Less common methods are steam or electrical tracing.

Piping

Jacketed piping is basically a pipe within a pipe.  Molten sulphur flows in the central or core pipe while steam flows in the annular space formed between the two pipes.   Sulphur piping will generally be carbon steel, seamless pipe supplied to ASTM A106 Gr. B and/or ASTM A53 Gr. B.   Standard sizes of jacketed pipe for molten sulphur are:

Core Pipe	Pipe Jacket	Flange
1"	2"	6" O.D. x 1" I.D.
1½"	2½"	7" O.D. x 1½" I.D.
2"	3"	7½" O.D. x 2" I.D.
3"	4"	9" O.D. x 3" I.D.
4"	6"	11" O.D. x 4" I.D.
6"	8"	13½" O.D. x 6" I.D.
8"	10"	16" O.D. x 8" I.D.

Schedule 80 pipe is recommended for pipe sizes 2" and smaller.

Schedule 40 pipe is recommended for pipe sizes larger than 2".

Valves

For on/off service, jacketed plug valves are generally used in molten sulphur service.  Two acceptable plug valves for this service are manufactured by XOMOX and Durco.  Both manufacturers offer partially and fully jacketed valves.  Partially jacketed valves provide uniform heat dissipation and is suitable for most applications because of the plug valve configuration and a certain amount of insulating effect of the PTFE sleeve.  Fully jacketed valves are for maximum heating or cooling duties without regard to uniform heating of surfaces in contact with the media.  For molten sulphur applications, partially jacketed valves are suitable provided insulation is maintained in good condition.

The valve body is generally cast steel with a ductile cast iron plug.  The plug rotates in a PTFE sleeve that is locked in the body by raised metal lips and grooves surrounding the body parts.

Partially jacketed valves are available in sizes from 25 mm to 300 mm (1" to 12") in the 150 lb. rating.  300 lb. rated valves are available from 25 mm to 200 mm (1" to 8") but are generally not required in most acid plant applications.

Valves smaller than 80 or 100 mm (3" or 4") will be wrench operated while larger valves are equipped with a gear operator.

	XOMOX	Durco
Tradename	Tufline	Sleeveline
Model No. (150 lb. rating)	067PJ (partially jacketed) 067FJ (fully jacketed)	PJG411 (partially jacketed) FJG411 (fully jacketed)
Size Range	25 to 300 mm (1" to 12") (PJ, 150 lb) 25 to 150 mm (1" to 6") (FJ, 150 lb)	25 to 300 mm (1" to 12") (PJ, 150 lb) 25 to 150 mm (1" to 6") (FJ, 150 lb)

Service Conditions

Molten Sulphur

Piping should be designed and rated for the maximum pump discharge pressure.  For plants operating with sulphur guns in the sulphur furnace, operating pressures can be quite high since a high spray nozzle pressure drop is required to finely atomize the sulphur.

Piping should be designed for a maximum temperature of 170ºC (338ºF).

A 2 mm corrosion allowance is recommended.

Steam Jacket

The operating pressure of the steam jacket will generally be 3.45 bar (g) (50 psig).  The system will be protected from overpressure by a relief valve located on the steam header downstream of the pressure reducing station.

The jacketing pipe should be designed for a maximum temperature of 170ºC (338ºF).

A 2 mm corrosion allowance is recommended.

Gaskets

Early piping system used 3 mm (1/8") compressed asbestos gaskets for flanged connections.  Many companies prohibit the use of asbestos so an alternative must be used.  Spiral wound gaskets to API Standard 601 made of 304 S.S. and flexible graphite are a good alternative. 

Steam Jumpovers

Steam jumpovers can be hard piped using standard carbon steel pipe fiittings, stainless steel tubing with 'Swagelok' type fittings or flexible hoses.  By far the easiest to install and maintain are flexible hose jumpovers.

Flexible jumpovers are either annular or helical flexible metal hose constructed of 300 series stainless steel for the hose and outer braid.  Flexible jumpovers can also be obtained pre-insulated.  Hoses come in standard lengths of 560, 760 and 1220 mm ( 22", 30" and 48").   Diameters of hose are 13, 19 and 25 mm (1/2", 3/4" and 1") diameter.