Symbol Key Reference Index
- Last UpdatedAug 19, 2025
- 7 minute read
This section lists all available symbol keys (SKEYs) in alphabetic order. Cross-references are given to the generic component types (GTYPEs) under which the user will find them described in the preceding sections of this appendix (if appropriate).
Each SKEY has an indication of whether or not it may be redefined, as explained in Basic Principles. For components which include spindles, the standard spindle type associated with the predefined SKEY is indicated, refer to Spindle SKEYS, for illustrations of these spindle types.
|
SKEY |
GTYPE |
COMPONENT |
USER DEFINABLE? |
SPINDLE TYPE |
|---|---|---|---|---|
|
AR** |
VALV |
Angled Pressure Reducing Valve |
Yes |
09SP |
|
AV** |
VALV |
Angled Valve |
Yes |
01SP |
|
AX** |
VALV |
Angled Relief Valve or Vent |
Yes |
02SP |
|
BA** |
PCOM |
Angle Block |
Yes |
|
|
BEFL |
BEND |
Flanged Bend |
No |
|
|
BO** |
PCOM |
Offset Block |
Yes |
|
|
BR** |
PCOM |
Return Block |
Yes |
|
|
BTFL |
BEND |
Flanged Bend with Tee |
No |
|
|
BU+D |
BEND |
Pulled Return Bend |
No |
|
|
BUFL |
BEND |
Flanged Return Bend |
No |
|
|
C3** |
INST |
3-Way Control Valve |
No |
13SP |
|
C4** |
INST |
4-Way Control Valve |
No |
13SP |
|
CA** |
INST |
Angled Control Valve |
Yes |
13SP |
|
CEBW |
COUP |
Butt Weld Elbolet |
Yes |
|
|
CESC |
COUP |
Screwed Fitting Elbolet |
Yes |
|
|
CESW |
COUP |
Socket Weld Elbolet |
Yes |
|
|
CFSC |
COUP |
Half Coupling - Screwed |
Yes |
|
|
CFSW |
COUP |
Half Coupling - Socket Screwed |
Yes |
|
|
CH** |
PCOM |
Hose Coupling |
Yes |
|
|
CK** |
VALV |
Check Valve |
Yes |
|
|
COCP |
COUP |
Compression Fitting Coupling |
Yes |
|
|
COSC |
COUP |
Screwed Fitting Coupling |
Yes |
|
|
COSW |
COUP |
Socket Weld Coupling |
Yes |
|
|
CPBW |
REDU |
Butt Weld Concentric Reducer |
Yes |
|
|
CPCF |
COUP |
Centre Flange |
Yes |
|
|
CPFL |
REDU |
Flanged Concentric Reducer |
Yes |
|
|
CPWP |
COUP |
Watertight Bulkhead and Deck |
Yes |
|
|
CPWT |
COUP |
Welded Sleeve thru Pipe |
Yes |
|
|
CPWW |
COUP |
Welded Sleeve thru Pipe |
Yes |
|
|
CRBW |
CROS |
Butt Weld Cross |
No |
|
|
CRCP |
CROS |
Compression Fitting Cross |
No |
|
|
CRFL |
CROS |
Flanged Cross |
No |
|
|
CRRF |
CROS |
Set On Reinforced Cross |
No |
|
|
CRSC |
CROS |
Screwed Fitting Cross |
No |
|
|
CRSO |
CROS |
Set On Cross |
No |
|
|
CRSW |
CROS |
Socket Weld Cross |
No |
|
|
CSBW |
REDU |
Butt Weld Concentric Reducer |
Yes |
|
|
CSFL |
REDU |
Flanged Concentric Reducer |
Yes |
|
|
CTBW |
REDU |
Butt Weld Concentric Reducer with Tee |
Yes |
|
|
CTFL |
REDU |
Flanged Concentric Reducer with Tee |
Yes |
|
|
CTSC |
REDU |
Screwed Fitting Concentric with Tee |
Yes |
|
|
CTSW |
REDU |
Socket Weld Concentric Reducer with Tee |
Yes |
|
|
CV** |
INST |
Control Valve |
Yes |
13SP |
|
CXBW |
REDU |
Butt Weld Concentric Reducer with Tee |
Yes |
|
|
CXFL |
REDU |
Flanged Concentric Reducer with Tee |
Yes |
|
|
CZBW |
REDU |
Butt Weld Concentric Reducer with Tee |
Yes |
|
|
CZFL |
REDU |
Flanged Concentric Reducer with Tee |
Yes |
|
|
DR |
INST |
Rupture Disc |
Yes |
|
|
EBSC |
ELBO |
Screwed Fitting (Male) Elbow |
No |
|
|
ELBW |
ELBO |
Butt Weld Elbow |
No |
|
|
ELCP |
ELBO |
Compression Fitting Elbow |
No |
|
|
ELSC |
ELBO |
Screwed Fitting Elbow |
No |
|
|
ELSW |
ELBO |
Socket Weld Elbow |
No |
|
|
EPBW |
REDU |
Butt Weld Eccentric Reducer |
Yes |
|
|
EPFL |
REDU |
Flanged Eccentric Reducer |
Yes |
|
|
ER** |
ELBO |
Reducing Elbow |
No |
|
|
ESBW |
REDU |
Butt Weld Eccentric Reducer |
Yes |
|
|
ESFL |
REDU |
Flanged Eccentric Reducer |
Yes |
|
|
ETBW |
ELBO |
Butt Weld Elbow with Tee |
No |
|
|
ETCP |
ELBO |
Compression Fitting Elbow with Tee |
No |
|
|
ETSC |
ELBO |
Screwed Fitting Elbow with Tee |
No |
|
|
ETSW |
ELBO |
Socket Weld Elbow with Tee |
No |
|
|
EUBW |
ELBO |
Butt Weld Return Elbow |
No |
|
|
EX** |
PCOM |
Expansion Bellows |
Yes |
|
|
EXBW |
REDU |
Butt Weld Eccentric Reducer with Tee |
Yes |
|
|
EXFL |
REDU |
Flanged Eccentric Reducer with Tee |
Yes |
|
|
EZBW |
REDU |
Butt Weld Eccentric Reducer with Tee |
Yes |
|
|
EZFL |
REDU |
Flanged Eccentric Reducer with Tee |
Yes |
|
|
FA** |
FILT |
Angled Filter |
Yes |
|
|
FI** |
FILT |
Straight-Through (In-Line) Filter |
Yes |
|
|
FLBL |
FLAN |
Blind or Blanking Flange |
Yes |
|
|
FLBL |
FBLI |
Blind or Blanking Flange |
Yes |
|
|
FLFL |
FLAN |
Flared Flange |
Yes |
|
|
FLLB |
FLAN |
Loose Backing Flange |
Yes |
|
|
FLOR |
ATTA |
Floor Penetration Type ATTA |
Yes |
|
|
FLOW |
Flow Arrow |
Yes |
||
|
FLRC |
FLAN |
Reducing Flange |
Yes |
|
|
FLRC |
FBLI |
Reducing Flange |
Yes |
|
|
FLRE |
FLAN |
Eccentric Reducing Flange |
Yes |
|
|
FLRE |
FBLI |
Eccentric Reducing Flange |
Yes |
|
|
FLRG |
LJSE |
Lap Joint Ring |
No |
|
|
FLSC |
FLAN |
Screwed Fitting Flange |
Yes |
|
|
FLSE |
LJSE |
Lap Joint Stub End |
No |
|
|
FLSJ |
FLAN |
Slip-on J-Type Welded Flange |
Yes |
|
|
FLSO |
FLAN |
Slip-on Flange |
Yes |
|
|
FLSW |
FLAN |
Socket Weld Flange |
Yes |
|
|
FLWN |
FLAN |
Weld Neck Flange |
Yes |
|
|
FO** |
FILT |
Offset Filter |
Yes |
|
|
FOSO |
FLAN |
Slip-on Flange with Orifice |
Yes |
|
|
FOWN |
FLAN |
Weld Neck Flange with Orifice |
Yes |
|
|
FPFL |
FTUB |
Fixed Length Pipe with Flanged Ends |
No |
|
|
FPPL |
FTUB |
Fixed Length Pipe with Plain Ends |
Yes |
|
|
FR** |
FILT |
Return Filter |
No |
|
|
FT** |
PCOM |
Flame Trap |
Yes |
|
|
FX** |
PCOM |
Flexible Hose |
Yes |
|
|
FY** |
FILT |
‘Y’-type Filter/Strainer |
Yes |
|
|
H3** |
INST |
3-Way Control Valve |
No |
12SP |
|
H4** |
INST |
4-Way Control Valve |
No |
12SP |
|
HA** |
INST |
Angled Control Valve |
Yes |
12SP |
|
HC** |
OLET |
Screwed Half Coupling |
Yes |
|
|
HC** |
OLET |
Socket Weld Half Coupling |
Yes |
|
|
HV** |
INST |
Control Valve |
Yes |
12SP |
|
IA** |
INST |
Angled Instrument |
Yes |
|
|
IDFL |
INST |
Flanged Instrument with Dial |
No |
|
|
IDPL |
INST |
Instrument with Dial |
No |
|
|
II** |
INST |
Instrument |
Yes |
|
|
IO** |
INST |
Offset Instrument |
Yes |
|
|
IR** |
INST |
Return Instrument |
No |
|
|
ITFL |
OLET |
Flanged Instrument Tee |
No |
|
|
JA** |
INST |
Two-Level Multiport Valve |
No |
|
|
JB** |
INST |
Two-Level Multiport Valve |
No |
|
|
JC** |
INST |
Two-Level Multiport Valve |
No |
|
|
JE** |
INST |
Two-Level Multiport Valve |
No |
|
|
JG** |
INST |
Three-Level Multiport Valve |
No |
|
|
JK** |
INST |
Two-Level Multiport Valve |
No |
|
|
JL** |
INST |
One-Level Multiport Valve |
No |
|
|
JM** |
INST |
Three-Level Multiport Valve |
No |
|
|
JN** |
INST |
Three-Level Multiport Valve |
No |
|
|
JO** |
INST |
Two-Level Multiport Valve |
No |
|
|
JP** |
INST |
Two-Level Multiport Valve |
No |
|
|
JT** |
INST |
One-Level Multiport Valve |
No |
|
|
JU** |
INST |
Three-Level Multiport Valve |
No |
|
|
JV** |
INST |
Two-Level Multiport Valve |
No |
|
|
JW** |
INST |
Three-Level Multiport Valve |
No |
|
|
JX** |
INST |
Three-Level Multiport Valve |
No |
|
|
JY** |
INST |
Three-Level Multiport Valve |
No |
|
|
JZ** |
INST |
Three-Level Multiport Valve |
No |
|
|
KABW |
CAP |
Butt Weld Cap |
Yes |
|
|
KACP |
CAP |
Compression Fitting Cap |
Yes |
|
|
KASC |
CAP |
Screwed Fitting Cap |
Yes |
|
|
KASW |
CAP |
Socket Weld Cap |
Yes |
|
|
L@BW |
BEND |
Butt Weld Lobster Back Bend |
No |
|
|
L@FL |
BEND |
Flanged Lobster Back Bend |
No |
|
|
LA** |
OLET |
Butt Weld Latrolet |
Yes |
|
|
LA** |
OLET |
Screwed Fitting Latrolet |
Yes |
|
|
LA** |
OLET |
Socket Weld Latrolet |
Yes |
|
|
LG** |
INST |
Level Gauge |
No |
|
|
M3** |
INST |
3-Way Motorised Valve |
No |
11SP |
|
M4** |
INST |
4-Way Motorised Valve |
No |
|
|
MA** |
INST |
Angled Control Valve |
Yes |
11SP |
|
MIBW |
BEND |
Butt Weld Mitred Bend |
No |
|
|
MIFL |
BEND |
Flanged Mitred Bend |
No |
|
|
MTBW |
BEND |
Butt Weld Mitred Bend with Tee |
No |
|
|
MTFL |
BEND |
Flanged Mitred Bend with Tee |
No |
|
|
MV** |
INST |
Motorised Valve |
Yes |
11SP |
|
NBSC |
COUP |
Screwed Nipple |
Yes |
|
|
NC** |
PCOM |
Non-Category Item |
Yes |
|
|
NC** |
SHU |
Non-Category Item |
Yes |
|
|
NI** |
OLET |
Plain End Nipolet |
Yes |
|
|
NI** |
OLET |
Screwed Fitting Nipolet |
Yes |
|
|
NRSC |
COUP |
Screwed Fitting Nipple |
Yes |
|
|
OP |
INST |
Orifice Plate |
Yes |
|
|
OTBW |
REDU |
Butt Weld Eccentric Reducer with Tee |
Yes |
|
|
OTFL |
REDU |
Flanged Eccentric Reducer with Tee |
Yes |
|
|
OTSC |
REDU |
Screwed Fitting Eccentric Reducer with Tee |
Yes |
|
|
PB+D |
BEND |
Pulled Bend |
No |
|
|
PF |
CLOS |
Fixed Length Pipe Block |
Yes |
|
|
PL |
PCOM |
Plug |
Yes |
|
|
PR |
INST |
Restrictor Plate |
Yes |
|
|
PV |
CLOS |
Variable Length Pipe Block |
Yes |
|
|
RA** |
INST |
Angled Relief Valve |
Yes |
02SP |
|
RBSC |
REDU |
Screwed Fitting Concentric Reducing Bush |
Yes |
|
|
RBSW |
REDU |
Socket Weld Concentric Reducing Bush |
Yes |
|
|
RCBW |
REDU |
Butt Weld Concentric Reducer |
Yes |
|
|
RCCP |
REDU |
Compression Fitting Concentric Reducer |
Yes |
|
|
RCFL |
REDU |
Flanged Concentric Reducer |
Yes |
|
|
RCSC |
REDU |
Screwed Fitting Concentric Reducer |
Yes |
|
|
RCSW |
REDU |
Socket Weld Concentric Reducer |
Yes |
|
|
RD |
VENT |
Rupture Disc |
Yes |
|
|
REBW |
REDU |
Butt Weld Eccentric Reducer |
Yes |
|
|
REFL |
REDU |
Flanged Eccentric Reducer |
Yes |
|
|
RESC |
REDU |
Screwed Fitting Eccentric Reducer |
Yes |
|
|
RF |
REDU |
Special Reducing Flange |
Yes |
|
|
RNSC |
REDU |
Nipple Fitting Concentric Reducer |
Yes |
|
|
RP |
PCOM |
Restrictor Plate |
Yes |
|
|
RV** |
INST |
Relief Valve |
Yes |
|
|
S3** |
INST |
3-Way Control Valve with Square Indicator |
No |
10SP |
|
S4** |
INST |
4-Way Control Valve with Square Indicator |
No |
10SP |
|
SA** |
INST |
Angled Control Valve with Square Indicator |
Yes |
10SP |
|
SB |
PCOM |
Spectacle Blind |
Yes |
|
|
SG** |
PCOM |
Sight Glass |
Yes |
|
|
SK** |
OLET |
Socket Weld Sockolet |
Yes |
|
|
SP |
PCOM |
Slip Plate |
Yes |
|
|
SR |
PCOM |
Slip Ring |
Yes |
|
|
SV** |
INST |
Control Valve with Square Indicator |
Yes |
10SP |
|
SW** |
OLET |
Butt Weld Sweepolet |
Yes |
|
|
T@BW |
BEND |
Butt Weld Lobster Back Bend with Tee |
No |
|
|
T@FL |
BEND |
Flanged Lobster Back Bend with Tee |
No |
|
|
TA** |
TRAP |
Angled Trap |
Yes |
|
|
TB+D |
BEND |
Pulled Bend with Tee |
No |
|
|
TEBW |
TEE |
Butt Weld Tee |
No |
|
|
TECP |
TEE |
Compression Fitting Tee |
No |
|
|
TEFL |
TEE |
Flanged Tee |
No |
|
|
TERF |
TEE |
Reinforced Tee |
No |
|
|
TESC |
TEE |
Screwed Fitting Tee |
No |
|
|
TESI |
TEE |
Reserved for pipe tappings |
No |
|
|
TESO |
TEE |
Set On Tee |
No |
|
|
TESW |
TEE |
Socket Weld Tee |
No |
|
|
TH** |
OLET |
Screwed Fitting Thredolet |
Yes |
|
|
TI** |
TRAP |
In-line Trap |
Yes |
|
|
TO** |
TRAP |
Offset Trap |
Yes |
|
|
TPUL |
TEE |
Pulled Tee |
No |
|
|
TR** |
TRAP |
Return Trap |
No |
|
|
TSBW |
TEE |
Butt Weld Swept Tee |
No |
|
|
TSCP |
TEE |
Compression Fitting Swept Tee |
No |
|
|
TSFL |
TEE |
Flanged Swept Tee |
No |
|
|
TSSW |
TEE |
Socket Weld Swept Tee |
No |
|
|
TU** |
PCOM |
Tundish or Funnel |
Yes |
|
|
UNBW |
UNIO |
Union - Butt Weld |
Yes |
|
|
UNIV |
PCOM |
Universal Skey for special fittings |
Yes. Refer to Isodraft. |
|
|
UNSC |
UNIO |
Screwed Fitting Union |
Yes |
|
|
UNSW |
UNIO |
Butt or Socket Weld Union |
Yes |
|
|
V3** |
VTWA |
3-Way Valve |
No |
01SP |
|
V4** |
VFWA |
4-Way Valve |
No |
01SP |
|
VB** |
VALV |
Ball Valve |
Yes |
03SP |
|
VC** |
VALV |
Check Valve |
Yes |
|
|
VD** |
VALV |
Diaphragm Valve |
Yes |
01SP |
|
VG** |
VALV |
Globe Valve |
Yes |
01SP |
|
VK** |
VALV |
Cock Valve |
Yes |
03SP |
|
VN** |
VALV |
Needle Valve |
Yes |
06SP |
|
VP** |
VALV |
Plug Valve |
Yes |
07SP |
|
VR** |
VALV |
Relief Valve |
Yes |
02SP |
|
VS** |
VALV |
Slide Valve |
Yes |
08SP |
|
VT** |
VALV |
Gate Valve |
Yes |
05SP |
|
VV** |
VALV |
Basic Valve |
Yes |
01SP |
|
VX** |
VALV |
Pressure Reducing Valve |
Yes |
09SP |
|
VY** |
VALV |
Butterfly Valve |
Yes |
03SP |
|
WF |
WELD |
Field Fitted Weld |
No |
|
|
WLC |
OLET |
Welded Circular Lug |
Yes |
|
|
WLR |
OLET |
Welded Rectangular Lug |
Yes |
|
|
WS |
WELD |
Site Weld |
No |
|
|
WTBW |
OLET |
Butt Weld Weldolet |
Yes |
|
|
WW |
WELD |
Shop Weld |
No |
|
|
X@** |
CROS |
Generic Y-type Cross with user-definable out- and off- legs |
Yes |
|
|
XA** |
INST |
Angled Pressure Reducing Valve |
Yes |
09SP |
|
XV** |
INST |
Pressure Reducing Valve |
Yes |
09SP |
|
Y@** |
TEE |
Generic Y-type Tee with user-definable out- and off- legs |
Yes |
|
|
01HG |
Hanger (As a basis for user-defined hangers; refer to Defining a New Hanger.) |
Yes |
Note: ** denotes any of the following connection types:
|
BW |
Butt Weld |
|
CP |
Compression Fitting |
|
FL |
Flange |
|
SC |
Screwed Fitting |
|
SW |
Socket Weld |
|
PL |
Plain |
|
@ |
in Bends, denotes the number of bend segments (range 1‑9) in X-type and Y-type Crosses/Tees, replaced by an integer in the range 1 to 4, 1 indicating the largest bore, 4 indicating the smallest bore. |
|
+ |
denotes the ratio of the bend radius to the pipe bore (range 1‑9) |