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The Vesselets are a contoured integrally reinforced insert branch connection. Available in butt-weld vesselets, socket-weld vesselets, and threaded & flanged vesselet configurations. Outlet size range to 60" in over 60 different alloys. Meets all the requirements of the applicable codes and standards.

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Product standards & features

Applicable standard range

SIZE 1/8 NPS - 72 NPS
CLASS STD, XS, XXS, S160, 3000, 6000, 9000, 5S, 10S

Applicable standards

Design MSS SP-97, ASME B31.1, ASME B31.3, ASME Section III
Inspection & testing MSS SP-97
Marking MSS SP-25

Applicable end finishes

Face to pipe MSS SP-97
Socket weld ASME B16.11
Screwed ends (NPT) ASME B1.20.1
Butt welding ends ASME B16.25

When you need:
• Fully interpretable radiographic or ultrasonic weld examination
• Longer life under cyclic fatigue loading
• An insert fitting that is fully engineered and supported by Markl fatigue tests, burst tests, finite element analysis and years of successful experience in actual service

• True butt-weld installation in header
• Outlets available in butt-weld, socket-weld, threaded & flanged configurations
• Designed for easy installation
• Low stress intensification factor (sif)
• Available in outlet size range to 60”
• Available in over 60 different alloys
• Meets all the requirements of the applicable codes & standards


Required for all Codes:
1. Header (run) size & schedule or wall thickness
2. Outlet size & schedule or wall thickness
3. Material
4. Quantity
Note: In the absence of any other information, WFI will supply fittings proven by burst test.
Applicable codes are B131.1, B31.3 & ASME III
For ASME VIII, ASME Sec. 1, B31.4 & 8, additional service conditions are required.
This enables WFI to insure that the Vesselet® provided meets the code requirements.
These codes do not accept product line proof testing. They, as well as some specifications,
require area replacement as proof of adequacy. These requirements are
project specific and require additional ordering information as listed below.
1. Design Code
2. Design temperature
3. Design pressure
4. Corrosion allowance (if applicable)