Status: Need is Closed

Sight glass for viewing inside a gas-tight vessel

Request Number

Point of Contact
Need was closed on
Jan 8

Siemens would like to add the capability of viewing inside their stainless steel gas-tight insulated switchgear vessels. They are seeking an optical interface that will be utilized for control of the switch position in the vessel. The interface must be able to be welded to the vessel. Ideally, the solution involves sight glasses but Siemens are open to any technology that meets the requirements.



There is a need for operators to be able to check the switch position inside stainless steel switchgear vessels. There are several different types of vessels which will require a range of angles of view. The optical interface will be welded to the vessel and then filled with insulating gas. Once the vessel is assembled, a density test will be executed via Helium leak test.

The annual demand will be 3000 pieces (with the option for a higher volume). The pre-series is planned for November 2019.

Key success Criteria
  • Gas-tight
  • The inner diameter of the interface should be maximum 22 mm and the length 40-60mm.
  • The diagonal viewing angle will be between 40 to 70° depending on the type of vessel.
  • The tightness is guaranteed for 35 years (leakage rate 1.0x10-6 mbar l/s).
  • Continuous operating temperature: -40°C to +70°C (welding process not considered).
  • Construction pressure of the tank 1.8 bar (abs).      
  • Corrosion resistance: Test method S3 according to IEC 60068-2-52, 2017.
  • Resistance to moisture and heat according to IEC 62271-304, Level 2.
Possible Approaches

Siemens is open to all solutions that meet the key success criteria.

Due Date
Jan 2
Items to be submitted

We are looking for concise, non-confidential proposals. The proposal should:

  • Describe the technical approach
  • Provide information on the performance of the technology (if available)
  • Include a description of the responding organisation or team and their experience.

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Gallery Moderator(s)
Dezarae Carver
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