Drums are cylindrical hollow steel vessels used in process plants as intermediate containers that receive liquid from distillation and condensing equipment. Drums also collect liquid from vapor circuits and pump it to the other process groups, disposal or product storage. They are also used for chemical and catalyst storage, steam generation and deaeration of boiler feed water.

Types of Drums

Drums are categorized into

a) Horizontally mounted

b) Vertically mounted

Drums are located within a process unit either adjacent to related equipment or as a standalone operation.

Drums are dictated by net positive suction head (NPSH), minimum clearance, common platforming and maintenance and operator access.

The first step in drum layout is setting the height of the drum. To do this the plant layout designer requires the following information

a) Drum dimensions

b) Type of heads

c) Support details

d) NPSH requirements of pump

e) Bottom outlet size

f) Minimum clearances

g) Location

To position nozzle locations the following information are required.

a) Process vessel sketch

b) Instrument vessel sketch

c) Piping and instrument diagrams

d) Plant layout specifications

e) Nozzle summary

f) Insulation requirements

g) Plot plan

Platform Arrangements

Platforms are required at drums for access to valves, instruments, blinds and maintenance access. For tall vertical drums, platforms are usually circular and supported by brackets attached to the shell of the drum.

Piping Arrangements

Piping at drums should be in conjunction with nozzle locations, platform arrangements and drums location to related equipment. Piping should be positioned to facilitate the installation of supports, with sufficient flexibility to absorb any excessive stresses during operation.

Drum Instrumentation

Level, pressure and temperature instruments are used to control the operation of the drum and should be placed in a position for optimum operation and maintenance. Instrument requirements are usually highlighted on an instrument vessel sketch furnished by the instrument engineer.


Maintenance of drums is limited to removal of such exterior components as large relief or control valves for off site repair. Handling of such items can be achieved by means of fixed davits or by mobile equipment.