Help decipher my compressor air tank tag.

[Strouty]

What do these letters mean? SHTH? HDTH?

 

[Mooky]

National Board (of boiler and pressure vessel inspectors) number is the Identifier for the manufacturer in accordance with the code.

W.P. is the maximum allowable working pressure MAWP, can't read the first number, looks like 200 psi. Safety relief valve must not be higher than this value.

SHTH is the shell thickness in inches
HDTH is the head thickness in inches. Heads are thinner due to the strength imparted by the shape.

 

[scw1991]

CRN = Canadian Registration Number
WP = working pressure
SHTH = Shell Thickness (in inches)
HDTH = Head Thickness (in inches, top and bottom of tank)

Most air tanks have 2:1 semi-elliptical tank heads

 

[Strouty]

Thanks guys.

 

[Jawsfree]

Trying to determine the tank size on this 1967 compressor tank. Here is what I found in the tag.
190979. ASME 1967. Max EP 200 lbs max temp 650 HD ELLIP 21 HEAD 144 SHELL 68 THE WAYNE PUMP COMPANY