Abbreviations

First off as a new member, let me say hello to everyone.I am looking for a standard list of abbreviations for P&ID instrument bubbles, etc. Such as 'PI' stands for PRESSURE INDICATOR. I had one and cannot locate it. THX

Hi my friend, Nice to meet you
first let me indroduce my self,
I'm Ashok. I'm a piping designer.

Some of abbrivations belw:

A
A - Ampere
A/C - Air Conditioning
A/H - After Hours
AB - As Built
AEC - Architecture, Engineering, and Construction
AFL - Above Floor Level
AFL - Above Finished Level
AG - Agricultural pipe drain
AGL - Above Ground Level
AHD - Australian Height Datum
AHU - Air Handler Unit
APPROX - Approximately
AS - Australian Standard
ASCII - American Standard Code for Information Interchange
ATF - Along Top Flange
B
B - Basin or Bottom
BLDG - Building
BNS - Business Network Services
BOT - Bottom
BQ - Bendable Quality
BSP - British Standard Pipe
BT - Bath Tub
BTM - Bottom
BW - Both Ways
C
C - C shaped steel purlin
C/C - Cross Centres
C.J. - Control Joint (or Construction Joint)
CAD - Computer Aided Design. Less commonly use is Computer Assisted Drafting.
CCTV - Closed Circuit TeleVision
CFW - Continuous Fillet Weld
CHS - Circular Hollow Section
CL - Center Line
CLG - Control Joint
CLR - Clearance
CMU - Cement Masonry Unit
CNJ - Construction Joint
COL - Column
COMMS - Communications
CONN - Connection
CONT - Continuous
CS - Cleaners Sink
CT - Controller
CTR(S) - Centre/S
CTRL - Control
CTRS - Centers
CU - Dental Cuspidor
CVR - Cover
°C - Degrees Celsius
D
DD - Design Drawing
DIA - Diameter
DIM - Dimension
DN - Diameter Nominal
DP - Down Pipe
DR - Dryer
DW - Dishwasher
DWG - Drawing
DWG(S) - Drawing/S
E
EA - Equal Angle (steel)
EF - Each Face
EL - Elevated Level
EL - Elevation
ELEC - Electrical
EQ - Equal
EQUIP - Equipment
EW - Each Way
EWB - Electric Water Boiler
EWC - Electric Water Cooler
F
FB - Footing Beam
F'c - Characteristic Concrete Strength
FCU - Fan Coil Unit
FFL - Finished Floor Level
FL - Floor Level
FOC - Fibre Optic Cable
FS - Far Side
FSBL - Full Strength Butt Weld
FTG - Footing
FTP - Fibre Termination Panel (fibre optical cable)
FW - Fillet Weld
FWF - From Web Face (steel)
G
GALV - Galvanized
GIS - Graphic Information System
GLAV - Galvanized
GSM - Global System of Moblie or "Groupe Speciale Mobile" in French
H
H - Prewash Hose Reel
HOR - Horizontal
HORIZ - Horizontal
HP - High Pressure
HWB - Hair Wash Basin
I
ID - Inside Diameter
IE - Invert Elevation
IL - Invert Level
IO - Inspection Opening
IP - Intersection Point
ISO - International Standard Organisation
J
JIS - Japanese Industry Standard
K
kHz - Kilohertz
K.J. - Key Joint
KS - Kitchen Sink
KWh - Kilo Watt Hour (metre)
L
L - Steel Angle
LAN - Local Area Network
LGX - Line Group Cross (Connector, fibre optical cable)
LH - Left Hand
LPG - Liquid Petroleum Gas
LT - Laundry Trough
M
m - Metres (English) or Meters
MAX - Maximum
MDF - Main Distribution Frame (Telecommunications)
MFR - Manufacturer
MHz - Megahertz
Micky Mouse - A toy project, of very low quality.
MIN - Minimum
MISC - Miscellaneous
M.J. - Movement Joint
mm - Millimetres
MS - Mild Steel
N
NC - Normally Closed
NET - Network
No. - Number
NOM - Nominal
NS - Near Side
N.S.O.P. - Not Shown On Plan
NTS - Not To Scale
NZS - New Zealand Standard
O
OA or O/A - Overall
OD - Outside Diameter
OPT - Optional
P
PCD - Pitch Circle Diameter
PFC - Parallel Flange Channel
PL - Plate
PT - Pressure Tapping
PVC - Poly Vinyl Chloride
Q
QTY - Quantity
R
R - Radius
RAD - Radius or radial
REF - Reference
REINF - Reinforcement
REQ'D - Required
REV - Revision
RH - Right Hand
RHS - Rectangular Hollow Section
RL - Reduced Level or Relative Level
S
S - Sink
SAN - Sanitary
SDU - Sanitary Disposal Unit
SF - Strip Footing
SHR - Shower
SHS - Square Hollow Section
SIM - Similar
SQ - Square
SS or S/S - Stainless Steel
SL - Structural Level
SSL - Structural Slab Level
STD - Standard
T
T - Top
TB - Tie Beam
TEMP - Temperature
TFC - Taper Flange Channel
THK - Thick
TO or T.O. or T.OFF - Top Off
TR - Laundry Trough
TUN - Tundish
TYP - Typical
U
U/S - Under Side
UA - Unequal Angle (steel)
UB - Universal Beam (steel)
UC - Universal Column (steel)
UNO - Unless Noted Otherwise (UON is prefered)
UON - Unless Otherwise Noted
UR - Urinal
V
VER - Vertical
VERT - Vertical
W
WAN - Wide Area Network
WB - Welded Beam (steel)
WC - Welded Column (steel)
WC - Water Closet (toilet)
WC(P) - Water Closet With 'P' Trap
WC(S) - Water Closet With 'S' Trap
WD - Working Drawing
WM - Washing Machine
WP - Water Proof or Work Point
X
X - By. Example, "N12 x 1200 long" also means "N12 by 1200 long".
Y
Z
Z - Zulu (Greenwich Mean Time)
Z - Z shaped steel purlin
Special Characters
°C = Degrees Celsius
Ø = Diameter
# = Number

Blimey Ashokaa,
That list included everything except the kitchen sink (actually it included that as well ha ha ha)
As entertaining as that list was, I'm not sure I've ever seen any of those abbreviations on a P&ID !!
Now with regards to the original post, there isn't a universal 'standard' for P&ID symbols.
Although PI will typically be a Pressure Indicator and TT will be a Temperature Transmitter , XI may be a pig signaller for one company or a corrosion coupon for another.
Rather than make an assumption it is always best to ask for the legend sheet that should be issued along with any P&ID's.
I've fallen foul of assuming that something on a P&ID is one thing, only to find out later on that it's something completely different that takes up 4 times as much room and should be located in an entirely different location !!

please be aware that THERE IS a standard for P&ID nominclature. There is a society that has the sole purpose of informing what the requirements of the P&ID are. The ISA (Instrument Society of America) published these requirements. A company will usually state that their P&ID's are per ISA standards. If a company chooses not to follow ISA standards, then they must be responsible to publish their own standards and nominclature.