Hello Baqar110
Gage Glasses are not required to be S-Stamped, see below ASME Official Interpretation: (Please note that correct paragraph in the current Code Edition is PG-11.4 instead of PG-11.3 while reading this interpretation)
Interpretation: I-89-06
Subject: Section I (1986 Edition, 1987 Addenda), PW-42, Welding Requirements for Gage Glasses
Date Issued: October 4, 1988
File Number: BC88-159
Related Documents:
Question (1): Are gage glasses considered to be part of the boiler proper as defined in Fig. PG-58.3.1?
Reply (1): No, they are part of the Boiler External Piping, subject to the rules of PG-60.
Question (2): May welded gage glass bodies be provided under the requirements of PG-11.3 by a manufacturer who does not possess a Section I Certificate of Authorization?
Reply (2): Yes.
Question (3): Must the welding for gage glass bodies, complying with a manufacturer's standard, meet the requirements of PG-11.3?
Reply (3): Yes.
Question (4): Does PW-42 apply to gage glasses?
Reply (4): Yes.
Javed Nasir
Inspection Engineer
Technip-France Abu Dhabi