Page 28 - Coulson Richardson's Chemical Engineering Vol.6 Chemical Engineering Design 4th Edition

11
INTRODUCTION TO DESIGN
sheets the basis of the calculations, and any assumptions and approximations made, in
sufficient detail for the methods, as well as the arithmetic, to be checked. Design calcula-
tions are normally set out on standard sheets. The heading at the top of each sheet should
include: the project title and identification number and, most importantly, the signature
(or initials) of the person who checked the calculation.
Drawings
All project drawings are normally drawn on specially printed sheets, with the company
name; project title and number; drawing title and identification number; draughtsman’s
name and person checking the drawing; clearly set out in a box in the bottom right-hand
corner. Provision should also be made for noting on the drawing all modifications to the
initial issue.
Drawings should conform to accepted drawing conventions, preferably those laid down
by the national standards. The symbols used for flow-sheets and piping and instrument
diagrams are discussed in Chapter 4. Drawings and sketches are normally made on
detail paper (semi-transparent) in pencil, so modifications can be easily made, and prints
taken.
In most design offices Computer Aided Design (CAD) methods are now used to produce
the drawings required for all the aspects of a project: flow-sheets, piping and instrumen-
tation, mechanical and civil work.

Specification sheets
Standard specification sheets are normally used to transmit the information required for
the detailed design, or purchase, of equipment items; such as, heat exchangers, pumps,
columns.
As well as ensuring that the information is clearly and unambiguously presented,
standard specification sheets serve as check lists to ensure that all the information required
is included.
Examples of equipment specification sheets are given in Appendix G.

Process manuals
Process manuals are often prepared by the process design group to describe the process and
the basis of the design. Together with the flow-sheets, they provide a complete technical
description of the process.

Operating manuals
Operating manuals give the detailed, step by step, instructions for operation of the process
and equipment. They would normally be prepared by the operating company personnel,
but may also be issued by a contractor as part of the contract package for a less experienced
client. The operating manuals would be used for operator instruction and training, and
for the preparation of the formal plant operating instructions.