Ethical issues in engineering design - 3TU.Centre for Ethics and ...

Piping and equipment
engineering company estimated that about 75% of the design process time at this
company was consumed by the process of detailing the design.
Designing piping and equipment can be considered middle to low level, normal
design (see section 2.3.1). Higher levels of the design process deal with the
specification of the product and the chemical reactions in the chemical
installation under construction. The overall design of the installation, including
flows of chemical substances and the pressure in different parts of the
installations, is a given constraint for the design process of the parts of the
installation. It is a normal design process because the equipment that will be
used and possible pipes are well known and have been used before. The
operational principle, layout and functional requirements are known at the start
of the design process. Standards and codes exist that prescribe the design or at
least provide the design process with guidelines. A problem that can arise is that
all these standards, codes, regulations, the customer’s requirements, practical
restrictions of the plant site, economic restrictions etc clash. For example, stairs
are required in installations that have a hydrogen sulphide flow. It is dangerous
to inhale the toxic hydrogen sulphide and therefore the total installation needs to
be accessible for people with tanks of compressed air on their back during an
accident. However, it is sometimes not possible to use stairs throughout the
whole installation due to a lack of space. In such a case a choice might be made to
have both stairs and a ladder, a ladder on one side of the installation and stairs on
the other side. The installation is accessible in emergency situations but space
has been saved. So, in piping and equipment design, the design problem is
sometimes over determined by external constraints. 1 Such over determination
might force engineers to change requirements or not to fulfil all of a customer’s
requirements. Criteria to evaluate options are available in this case so the
problem is reasonably well-structured. However, possible over determination
prevents a piping and equipment design problem being really well-structured in
all cases. Requirements may have to be adapted to arrive at a solution to the
design problem.
5.2 Regulation regarding pressure vessels and piping
Different regulations play an important part in the design and use of (petro)
chemical installations. The regulations, codes and standards that play a part
during the design process of piping and equipment in the (petro)chemical
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1 I use over determination here in the sense that there are requirements that cannot possibly be
complied with simultaneously. Certain options comply with certain requirements and it is not
possible to find an option that complies with all requirements.
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