Connections; Direction Of Safety Valves; Flow-Through; Condensation - Leser 411 Instructions De Service

The following precautions should be taken:
•
The system must be able to expand
•
Pipe runs must not be fixed in a way that
they are under tension.
•
The safety valve brackets should be used
for attaching the valve securely to the
plant.
•
E Vibration of the safety valve and plant
should be prevented.

12.4 Connections

The connections/seals between the safety
valve and the plant shall be of sufficient size.
They also have to be designed in accordance
with the sets of rules to prevent the
connection from failing (also refer to sections
4 and 8).
The user is responsible for the correct fitting
of seals for pipes leading into the valve and
pipes for blowing-off or other connections to
the safety valves. Therefore LESER will not
accept any liability for these.
For correct installation the user should ensure
that the flange sealing surfaces are not
damaged during installation.

12.5 Direction of safety valves

Confirmation by the TÜV Nord:
Directly-loaded safety valves are to be
installed in accordance with AD 2000-
Merkblatt A2 "upright with respect to the flow
direction":
In addition AD 2000-Merkblatt A2 requires
that "safety valves must correspond to the
state-of-the-art and be suitable for the
purpose for which they are deployed".
Under the following conditions it is possible to
deviate from the upright installation direction,
and in our view it is also permissible.
E.g., the safety valves have been granted
type approval for non-upright installation and
a note to this effect is found in the VdTÜV-
Merkblatt.
If adequate experience of installing safety
valves in a direction other than upright is
available over an extended period, this type of
installation is permissible if agreed between
operator, manufacturer and the technical
inspector, who authorises the installation. If
applicable, additional measures may need to
be taken with regard to this installation.
Therefore safety valves may, according to the
information provided above, be installed in
directions other than the one specified in
AD 2000-Merkblatt A2.
If the conditions mentioned above have been
fulfilled, the following points have to be
24
observed when installing the valve in a
direction other than upright:
•
Drainage has to be fitted to drain medium
or condensation from components which
are important for the function of the valve.
•
Servicing procedures should be modified,
e.g., the functioning of the drainage
system must be ensured.
•
LESER must be informed about the type
of installation in order to be able to agree
to a direction deviating from upright.

12.6 Flow-through

The flow direction must be observed during
installation. It can be recognised by the
following features:
•
Flow direction arrow on the body
•
Diagrams in the
Complete Catalogue
-
Operating instructions
-
Data sheets and
-
Assembly instructions.
-

12.7 Condensation

Medium or condensation must be drained
from the outlet chamber of the safety valve or
such components, which are important to the
functioning of the valve (spring, bellows etc.).
The following points should be noted:
•
Drainage should always be carried out via
the blow-off pipe, which should be
installed sloping downwards so that it can
drain itself (figure 3).
•
Directly downstream of the safety valve
there must be no upward bend as in this
case correct drainage would not be
possible (figure 4).
•
The blow-off pipe must be provided with a
sufficiently large condensation drainage
pipe, which must be attached to the
lowest point of the pipe. For pipes larger
than nominal diameter 40 mm the
drainage pipe must have a nominal
diameter of at least 20 mm. (In case of
steam applications even larger diameters
may be necessary. In such cases the
regulations must be observed).
•
LESER safety valves are not provided
with a drain hole as the drainage must be
executed via
Exceptions: Certain regulations require
drainage holes (e.g., on ships with
variable orientation in the water and a
pipe slope). Safety valves which are
intended for such purposes are equipped
with a drainage hole. Such designs are
only manufactured if they are specifically
ordered.
the blow-off pipe.
24