16
SINCE 1962, MOST PRV MANUFACTURERS HAVE OVERSTATED THEIR “K” VALUES AND UNDERSTATED THEIR “A” VALUES.
17
National Board NB-18 ‘Red Book’

12
NB Method of Certifying Capacity
■ Calculate the average “KD” for the 9 test valves
No test valves “KD” can deviate more than ±5% from the average
■ Establish the ASME “K” K = Average KD x 0.90 ■ The nozzle coefficients “KD” and “K”, and orifice area “A” are published for all certified SV in the NB “Red Book”
MULTIPLE VALVES
116
16%
1ST valve: Max SET MAWP Sizing at 116%
(16% overpressure)
110
2ND, 3RD … 1ST
105
2ND , 3RD … valves: Max SET 105% MAWP Sizing at 116%
(10% overpressure)
ASME VIII Set Pressure Tolerance
UP TO 70 PSIG [4.83 barg] SET ---- ± 2 psig [0.14 barg] OVER 70 PSIG [4.83 barg] SET ----
± 3%
NAMEPLATE SET PRES.
ASME VIII, Blocked Discharge
MAWP (MAX. SET)
NB
NATIONAL BOARD OF BOILER AND PRESSURE VESSEL INSPECTORS “THE COPS”
ENFORCEMENT LAW JURISDICTIONS EXEMPTIONS
10
WE CAN PROVIDE PRVs BUILT TO HE REQUIREMENTS OF ASME SECTION VIII AND SET LOWER THAN 1.03 barg
BUT WITHOUT A CODE STAMP
11
THE ASME DOES NOT CERTIFY OR APPROVE ANY DEVICE
The NATIONAL BOARD certifies valve Capacity and verifies valve compliance with the ASME Code
National Board NB-18 ‘Red Book’
■ NB-18 viewed on line or downloaded
All data on each and every valve (& RD) certified per ASME codes (I, III & VIII)
K=Kd x 0.90
III : Nuclear (US) IV : heating boilers V : NDE VI : care of heating boilers
3
ASME Section VIII
CAN APPLY ONLY TO VALVES SET 1.03 barg [15 psig] & HIGHER
All secondary pressure parts
1.5 times design pressure
■ Seat tightness
Per API Std 527
22
Copyright © 2010 Tyco Flow Control. All Rights Reserved
Functional Test and Setting
ASME Pressure Vessel Code
Qingpu PRV Seminar March 2011
Code? Standard?
■ ASME Section VIII and others…
US code = the LAW like European PED… out of US = customer requirement
24
Copyright © 2010 Tyco Flow Control. All Rights Reserved
15
For Gas Flow (example)
M W = CKAP KA TZ
The NB allows published deviations from “K” and “A” values in the “RED BOOK”. However:
Published KA ≤ ASME KA (NB “Red Book”)
Water or similar
■ Repair, changes…
Must be done by ASME certified repair shop (VR)
23
All settings must be sealed (wire + lead)
Copyright © 2010 Tyco Flow Control. All Rights Reserved
21%
1ST valve: Max SET MAWP Sizing at 121%
(21% overpressure)
2ND, 3RD … 121 1ST
2ND , 3RD … valves: Max SET 110% MAWP Sizing at 121%
(10% overpressure)
100
Lift Lever
■ ASME requires a lift lever on
Air Steam Hot water >60ºC
■ But for pilot operated safety valve:
Field Test Connection is accepted in lieu of lift lever
13
K and A
■ During certification
A is measured Smallest section in the flow path (throat) Actual flow is compared to theoretical flow through perfect nozzle (K=1) Wactual/Wtheor= Kactual K=0.9 x Kactual
Actual Areas
Spring Range
■ PRV must be capable of being re-Set by +/- 5% from factory nameplate set pressure with no change of parts or loss of performance
ONE VALVE ONLY
ALLOWED ACCUMULATION:
110 ONE PRD
10%
or 3 PSIG, [0.20 Barg] whichever Is Greater 100
MAWP (MAX. SET)
ASME VIII, Blocked Discharge
ALLOWED ACCUMULATION:
Nameplate set = 1000. kPag
● 16.1 barg
Can be reset on site to 950 to 1050 kPag
5%
15.3 barg
On site (used valve)
13.2 barg 12.5 barg
20
Published Spring Range (new valve) 5%
■ API
mainly oil and gas market recommendations, standards (NF, DIN…) not mandatory but customer requirement
2
Copyright © 2010 Tyco Flow Control. All Rights Reserved
14
Copyright © 2010 Tyco Flow Control. All Rights Reserved
In 1962, the code was revised Requiring that 10% safety factor be used in calculation: K = 0.9 x KD
21
Copyright © 2010 Tyco Flow Control. All Rights Reserved
Production Tests Required
■ Hydrostatic test
All primary pressure parts
1.5 times design pressure
■ Gas valves:
Air or similar
■ Finished!
Nameplate to show Set, Capacity, Manufacturer’s name… and ‘UV’ stamp
■ Steam valves:
Steam (if possible)
■ Liquid valves:
ASME, US Press.Vessels Code