Chemical Engineering October 2010 - 48

Table. Ra Readings foR PRoducTconTacT
suRfaces
Engineering Practice
well as other segments of the process
stream, to prevent residue buildup on
equipment and piping.
When designing a process that requires
CIP or SIP capabilities, there
are specific piping and equipment design
requirements that need to be met.
These include requirements related to
minimum slope, maximum acceptable
dead-leg, internal weld finish, fitting
and fabrication tolerances, surface finishes,
and so on. These are all design
considerations needed to accommodate
CIP or SIP protocols. The design
attributes needed to integrate CIP
and SIP into a system can be found in
the BPE Standard.
Sloped piping and maximum acceptable
dead-leg criteria. Similarly,
designing a process system that
may not necessarily be concerned
with bacteria may still have a need for
sloped piping and maximum acceptable
dead-leg criteria. The criteria for
these design elements exists as vetted
information within the BPE Standard,
and thus can simply be referenced in
a specification drawn from the BPE
Standard, rather than basing design
criteria on some arbitrary rule-ofthumb
principal.
Documentation requirements.
Meanwhile, while facilities that are
outside the realm of strict biopharmaceutical
manufacturing may not
require the same exacting documentation
trail all CPI facilities do require
varying degrees of documentation related
to material, fabrication, examination,
and testing. Nonetheless, facilities
whose documentation records
are not required to be as extensive as
those required by the biopharmaceutical
industry can still benefit from the
portion of the standard that relates to
documentation requirements.
Specifically, the laundry list of documentation
that is specified in the BPE
Standard can be utilized by other industries
simply by selectively referencing
that part of the standard. Rather
than a company having to write out a
proprietary requirement - one that
may already be contained in a vetted
industry standard - the company can
simply reference the respective segment
of the standard that spells out
the needed requirement.
Mechanically polished
Ra max.
Surface
µ-in
Content of the standard
As noted earlier, while the BPE
Standard dovetails with, and references
to, many aspects of B31.3,
it is markedly different in both
layout and content. Nonetheless,
the discussion below shows how
universal the nine current parts
of the BPE Standard are for many
diverse facilities throughout the
CPI.
Part GR - General Requirements.
This section sets the tone
and defines the scope of the standard.
It defines terms that are
specific to the bioprocessing industry
and other terms that may
have originated elsewhere and
been adopted by the BPE standard
with a slightly different interpretation.
Part
SD - Design for Sterility
and Cleanability. Part SD
provides discussion on how to design
cleanability and sterility into a system.
It also covers specific design issues
with regard to instrumentation,
hose assemblies, filtration and other
equipment. In addition to hydrostatic
testing, this section also touches on
testing fundamentals for spray balls,
drainability, cleanability and sterility.
It also provides a listing of documentation
that can be selected by, and used
for, industries beyond bioprocessing.
This section is one place in which
the BPE Standard diverges from the
main focus of the B31.3 format. For
instance, while B31.3 is developed
around the cornerstone of safety and
system integrity, the BPE, while integrating
safety and integrity, is focused
mainly on providing acceptable criteria
for system design.
Since its inception, the SD subcommittee
has taken on the task of researching
accepted industry design
practices that are currently being used
in the bioprocessing industry. This is
an effort to validate, and, where necessary,
rectify those largely unqualified
design practices and criteria, through
the development of new and appropriate
design criteria for adoption into
the BPE Standard.
Part DT - Dimensions and Tolerances.
This section has basically
standardized many of the practices
in the bioprocessing industry. Prior to
48 ChemiCal engineering www.Che.Com oCtober 2010
designation
SF0
SF1
SF2
SF3
Ra max.
SF4
SF5
SF6
No finish requirement
20
25
30
µ-in.
15
20
25
µm
No
finish requirement
0.51
0.64
0.76
Mechanically
polished1 and electropolished
µm
0.38
0.51
0.64
General
notes: (a) This table replaces previously
published Tables SF02, SF-4, SF-6, SF-8, and SF-10.
(b) All Ra readings are taken across the lay, wherever
possible.
(c) No single Ra reading shall exceed the Ra max
value in this table
(d) Other Ra readings are available if agreed upon
between owner/user and manufacturer, not to exceed
values in this table.
Note: (1) or any other finishing method that meets
the Ra max
Source: ASME-Bioprocessing Equipment (BPE) Standard.
the availability of the BPE Standard
and Part DT, there were no industrystandard
dimensions on fittings and
valves, and no common set of manufacturing
tolerances. This meant that
components from one manufacturer
to the next were not necessarily interchangeable
- a situation that has
long presented a nightmare for many
projects - and that all fittings had to
be purchased from the same manufacturer
to ensure compatibility.
Part MJ - Material Joining. This
section touches on all aspects of the
welding of pressure vessels, tanks,
tubes and fittings, and provides guidance
on acceptable requirements
related to material selection, inspection,
examination and testing. It also
discusses joining processes and procedures,
weld joint design and preparation,
weld-acceptance criteria, procedure
and performance qualification
and documentation requirements.
Several tables list weld-acceptance criteria,
and detailed graphics illustrate
acceptable and unacceptable welds.
Part SF - Surface Finish. A crucial
element in the ability to attain
and maintain a clean system is in the
quality of the finish on the productcontact
surface. Whether in the bioprocessing
industry or other sectors
in which at least a segment of the
processing scheme involves bioprocessing
(such as biofuels production),
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Chemical Engineering October 2010

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