60 |
Baker Hughes
© 2020 Baker Hughes Company. All rights reserved.
XXII. 2900-40 Series POSRV Options (Cont.)
B. Dual Pilots
A dual pilot arrangement (Figure 46) is available for
applications in which the pilot valve soft goods require
monitoring and/or maintenance more often than the main
valve. In this installation, the pilot valves may be alternated
for maintenance, without bringing the system down.
ATTENTION!
!
When servicing dual pilots, procedures need to be in
place to perform a tag out / lock out of pilots under
pressure if they are in service.
C. Field Test Connection
A field test connection is standard on all pilot valve types.
This allows the stroking of the valve with an auxiliary
media, e.g. air or nitrogen. An internal check valve is
present in the field test connection isolating the inlet
media from the test media and at the same time, allowing
the valve to open normally in the event of a system over
pressurization during a field test. The test port connection
is a .375” (9.53 mm) tube fitting equipped with a bug
screen.
For all applications on air, water over 140°F (60 °C), or
steam service, ASME Section VIII - Division 1 requires
each pressure relief valve to have a lifting device such as a
field test connection or a means of connecting or applying
pressure to the pilot to verify that the moving parts
essential to good operation are free to move. (Reference
UG 136(a)(3)). The lifting lever or field test connection
may be omitted under Code Case 2203. All orders for
pressure relief valves without levers or field test connection
for steam, air and water over 140°F (60°C) must state
specifically that the valves are being purchased per Code
Case 2203. The purchaser is responsible for obtaining
jurisdictional authorization for use of Code Case 2203.
D. Single, Dual and High Capacity
Filters (Optional)
Filter options are available for dirty applications. These
filters are installed in the pilot inlet sensing line. For the
39PV, an optional sensing line filter is available (Figure
46). This filter has a 316 stainless steel body, Teflon
®
seals, and a 40-50 micron stainless steel filter element.
Other high capacity filter options (Figure 48) include:
1. A carbon steel cadmium coated filter body with a 35
micron stainless steel element; and
2. An entirely stainless steel filter arrangement. These
filters may be equipped with a manually operated
needle valve which allows for purging the filtered
material while the valve is in operation. All filter
elements are stainless steel, and all filters, including
carbon steel, conform to NACE Standard MR0103
and MR0175. A dual filter arrangement (Figure 49)
Figure 47: Sensing Line Filter
Figure 46: Dual Pilots