Hydrocarbon Processing - April 2021 - 53

Engineering and
Construction
P. DIXIT, Boroda India, Vadodara, Gujarat, India

Challenges and pitfalls in brownfield EPC projects
Job requirements and scope are well
defined in engineering, procurement
and construction (EPC) contracts because they are designed and engineered
from scratch. Owners prefer to get work
done through EPC contracts as it helps
them in obtaining a firm cost and time
commitment.
Executing a brownfield project in a
process plant presents many challenges
and complexities due to unknowns and
potential variations. Major factors include the non-availability of old data
drawings, design calculations and updated/as-built drawings.
Normally, small brownfield projects
are preferred on a cost-plus basis, as engineering and execution go side by side
and uncertainties are identified as the
job progresses.
Considering the advantages of an
EPC contract, owners usually prefer to
pair brownfield work with any upcoming greenfield expansion projects. This
makes the project attractive to an EPC
contractor, and the owner can also get
firm cost and schedule commitments.
Time issues becomes more complex
when more than one or two EPC contracts are awarded in the same or adjoining field, sharing some common facilities, space and working areas. In such
cases, the interdependency of the two
contractors also increases.
Some of the challenges and lessons
learned while executing such hybrid projects are presented here. Although these
issues may appear to be standard, they
can have serious consequences if not considered during a cost estimation. Normally under such contracts, the owner and its
team (or PMC) earnestly intend to provide all details at the enquiry stage. However, they try to cover any out-of-sight
discrepancies by using a typical clause:

" Details provided in the inquiry
document are the best possible at
the time of release of this document.
However, these are subject to
field verification by the contractor
prior to submission of bids. Unless
any exceptions or deviations are
put forward by the contractor
and accepted by the owner, any
subsequent changes later shall
not be acceptable, and time and
cost implications shall be to the
contractor's account. "
Some common types of design and execution challenges are detailed here.
Process area. Process conditions at
the battery limits of any operating plant

are dynamic and expected to have variations that must be detailed in the inquiry
for the contractor to conduct a hydraulic
check. In a project, due to this omission,
one acid gas collection required an increased stainless-steel header size at a late
stage; as available gas came to it from different units, the pressure was insufficient
to reach to the downstream sulfur recovery unit (SRU).
In an integrated analysis of a complementary brownfield with greenfield project, complete hydraulics and pressure
balancing is required for systems like air,
cooling water, steam, flare, etc. In another
project, a problem was encountered with
cooling water supply pressure and quantity, resulting in the augmentation of the
old plant cooling water system.

Existing pipe rack

Pipe rack

Distance very close
Sheet pile

GL EL

Concrete pit for
underground
vessel

GL EL

FIG. 1. During excavation, sheet piling was used to protect the foundation of a pipe rack.
Hydrocarbon Processing | APRIL 2021

Hydrocarbon Processing - April 2021

Table of Contents for the Digital Edition of Hydrocarbon Processing - April 2021