A key safety aspect when engineering process plants is the efficient prevention of impermissibly high overpressures in the process systems when malfunctions occur. In many cases, this can only be ensured by installing safety valves or general mechanical pressure relief devices. The weyer group has had extensive experience in the dimensioning of safety valves, as well as of the downstream systems required to divert and dispose of the substances produced. The entire range of services in terms of selecting and designing or recalculating these systems, is briefly described in the following.

1. SAFETY VALVES
weyer group
allround. smart.
weyer special | safety valves
www.weyer-group.com

2. • Fire in the vicinity of the plant
In the course of determining the blow-
down cases, the extent to which alterna-
tive measures can be effectively taken to
prevent those impermissible pressure in-
creases, can also be examined. Alternative
measures to be used in this context could
be, for example, instrumentation & control
systems.
A key safety aspect when engineering process plants is the efficient prevention of impermissibly high overpressures in
the process systems when malfunctions occur. In many cases, this can only be ensured by installing safety valves or
general mechanical pressure relief devices. The weyer group has had extensive experience in the dimensioning of safety
valves, as well as of the downstream systems required to divert and dispose of the substances produced. The entire range
of services in terms of selecting and designing or recalculating these systems, is briefly described in the following.
What we offer:
 Determination of blow-
down cases
 Selection and dimen-
sioning or recalculation
of pressure relief devices
 Selection and design of
downstream systems
 Complete support
1 Determination of blow-
down cases
When determining the blow-down cases,
we examine which malfunctions during
plant operation can lead to impermissible
pressure increases in the system. These
examinations are often performed in con-
junction with or based on a safety study
(e.g., HAZOP or PAAG).
 Possible causes that can lead to a
blow-down are, for example:
• Faulty closing or opening of valves
(automatic / manual)
• Faulty control / defective measur-
ing systems
• Pipe rupture in heat exchangers
• Failure of utilities (e.g., power,
cooling water, auxiliary energy for
valves)
Safety valves
weyer special | safety valves | page 2
weyer special | safety valves

3. 4 Complete support
Apart from the calculation, all further
planning steps in the course of the pro-
curement, installation or replacement of
safety valves can then be performed by
the weyer group.
3 Selection and design of
downstream systems
The substance mixtures to be discharged
can often not be exhausted into the atmo-
sphere untreated, but must be conducted
to a suitable treatment system. In the ma-
jority of cases, the installation of a flare-
gas network with knock-out drum and
flare is the method chosen. To design
these networks, the weyer group uses a
variety of rigorous simulation programs,
including one developed by the weyer
group itself.
2 Selection and dimensio-
ning or recalculation of
pressure relief devices
Based on the blow-down cases deter-
mined, appropriate pressure relief devices
are selected and dimensioned. An impor-
tant aspect during design is taking into
account any two-phase flows that may
occur. These can occur in plants in which,
during normal operation, two-phase mix-
tures are handled or if, in the case of a
blow-down, fluids are entrained with es-
caping gases and vapors.
When dimensioning the pressure relief
devices, particularly for two-phase flows,
current national and international stan-
dards e.g., DIN EN ISO 4126 , API 520 /
521, AD 2000) are taken into account. The
weyer group has developed its own calcu-
lation system for this.
Finally, the actual pressure losses in the
feed and discharge lines are calculated. In
the case of recalculations, if necessary, a
survey of the pipelines / pipeline networks
is performed on site.
Normally, the substance data required for
the calculation is obtained by using
process simulators.
weyer special | safety valves | page 3
weyer group
allround. smart.
Your benefits:
 Exclusion of organizational responsi-
bility
 Determination of the relevant blow-
down cases
 Selection and dimensioning / recalcu-
lation of pressure relief devices
 Uniform documentation, indepen-
dently of the plant constructor or sup-
pliers of the pressure relief devices
 Selection and design of downstream
systems

4. The weyer group is a group-independent corporate association of engineering and con-
sulting companies in Germany, Austria and Switzerland.
Since its establishment over 30 years ago, the weyer group has developed a wide range of
expertise which has always been based on the expectations and wishes of our clients.
weyer group
allround. smart.
www.weyer-group.com
Your contact
www.weyer-group.com
References:
 Boehringer Ingelheim Pharma GmbH Co.KG
 DHC Solvent Chemie GmbH
 Mineraloelraffinerie Oberrhein GmbH Co.KG
 PCK Raffinerie GmbH
 Shell Deutschland Oil GmbH
 Vopak Dupeg Terminal Hamburg GmbH
 Wilhelmshavener Raffineriegesellschaft mbH
Illustrations with friendly permission obtained
through LESER GmbH Co. KG Hamburg