What's RFSF? 5

[sks4338]

What do you mean by "RFSF" when you specify flanges?

Maybe I think it's raised face smooth finish.

Am i right?

 

[pennpiper]

Yes, That is correct.
RFSF = Raised Face Smooth Finish

 

[jsummerfield]

Really? Where do you find this nomenclature? It could as easily be serated flange, separable flange, etc. I poked around MSS SP-6 and ASME B16.5 and found nothing to support this. I also searched for RFWN (I use this all the time) and found nothing.

John

 

[CARF]

perhaps ask these guys?

http://www.welding-units.co.uk/start.htm

Good luck,

 

[NozzleTwister]

pennpiper is correct. RFSF means Raised Face Smooth Finish but this isn't official terminology that you'll find in the published codes.

Back in the old days the standard finish on raised face flanges was around 500 microinch roughness. Some users and licensors (UOP for one) desired a smoother flange finish for services like hydrogen to get a better flange seal when used with spiral wound gaskets. The term RFSF was used to differentiate these smooth face flanges from those with the rougher standard finish. When an RFSF flange is specified, the required finish should also be defined. I remember seeing finishes like 63-125Ra or 125-250Ra.

In recent editions of ASME B16.5, the standard finish is defined as 125-250 Microinch average. Because the standard finish is now much smoother than before, the RFSF requirements have pretty much been abandoned. You'll find that the smooth finish requirement for flanges and valves in most old piping specifications are equivalent or close to the standard finish for flanges today.


NozzleTwister
Houston, Texas

 

[alamin]

Worth double checking it is not a typo for commonly used RFSO (Raised Face Slip On) flange. Does the flange specification mention what type of flange it is (Weld neck, slip on, etc)?

Cheers,
Amin

 

[JJPellin]

I have built this list of abreviations over the years. It usually has what I am looking for.

ANSI American National Standards Institute
API American Petroleum Institute
ASME American Society of Mechanical Engineers
ASSY Assembly
ASTM American Society of Testing Materials
AVG Average
BB Bolted Bonnet
BC Bolt Circle
BF Blind Flange
BLDG Building
BM Bill of Material (Also BOM)
BOP Bottom of Pipe
BW Butt Weld
CI Cast Iron
CO Clean Out
CONC Concentric
COND Condensate
CPLG Coupling
CS Carbon Steel or Cast Steel
CSC Car Sealed Closed
CSO Car Sealed Open
°C Degrees Celsius
°F Degrees Fahrenheit
DI Ductile Iron
DIA Diameter
DWG Drawing
ECC Eccentric
ELEV Elevation
FF Full Face
FIG Figure
FLG Flange
FOB Flat on Bottom
FOT Flat on Top
FS Forged Steel
FT Feet or Foot
FW Field Weld
GALV Galvanized
GR Grade
HDR Header
ID Inside Diameter
INS Insulate
INV Invert (Inside Bottom of Pipe)
IPS Iron Pipe Size
I-ST Insulate and Steam Trace
LBS Pounds
LR Long Radius
M&F Male and Female
MFG Manufacturer
MI Malleable Iron
MIN Minimum
NC Normally Closed
NO Normally Open
OD Outside Diameter
PE Plain End
PSIA Pounds per Square Inch Absolute
PSIG Pounds per Square Inch Gauge
RB Return Bend
RED Reducer
RF Raised Face
RTJ Ring Type Joint (Also RJ)
SCH Schedule
SCRD Screwed
SF Smooth Finish
SMLS Seamless
SO Slip-On
SOL Sock-O-Let
SPEC Specification
SR Short Radius
SS Stainless Steel
STD Standard
STL Steel
STM Steam
SW Socket-Weld
SWG Swage
TE Threaded End
TEMP Temperature
TOC Top of Concrete
TOG Top of Grade
TOL Thread -O-Let
TOS Top of Steel
TYP Typical
VERT Vertical
W/ With
WE Weld End
WN Weld Neck
WOL Weld-O-Let
WT Weight
XH Extra Heavy (Also XS)
XXH Double Extra Heavy (Also XXS)