Description
Pipeline isolation line blank
ASTM A240 316L Spectacle Blind Flange
An ASTM A240 316L spectacle blind is a corrosion-resistant figure-8 line blank machined for pipeline isolation between compatible flanges.
What is a 316L spectacle blind flange?
The solid plate blocks flow while the open ring maintains flange spacing when the line is returned to service. One-piece construction gives a clear external indication of line status.
316L contains molybdenum and is often chosen over 304L for improved pitting and crevice-corrosion resistance, subject to actual chloride level and temperature.
316L spectacle blind flange specifications
| Product | spectacle blind flange |
|---|---|
| Material | 316L / UNS S31603 / EN 1.4404 |
| Material specification | ASTM A240 Type 316L |
| Dimensional standard | ASME B16.48 |
| Connection / form | Figure-8 line blank installed between mating flanges |
| Size and rating | ASME sizes and pressure classes subject to the selected material, facing and standard limits |
| Surface / end detail | Raised-face or ring-joint-compatible finish as ordered |
| Manufacturing route | Plate cutting, CNC machining, facing and identification |
| Inspection documents | EN 10204 3.1 MTC, dimensional report and additional testing when specified |
Dimensions, tolerances and acceptance criteria follow the standard edition and project documents named on the purchase order. Published ranges are enquiry guidance, not a pressure-temperature design approval.
Material and dimensional standards
Material specification
ASTM A240 Type 316L is plate material with UNS S31603. EN 1.4404 is a common European reference but is not a substitute for a complete purchase specification.
Product dimensions
ASME B16.48 defines line blanks used between flanges. The ordered pressure class, facing and dimensional details must match the mating flange system.
Typical applications and selection boundary
Applications are examples only. Confirm corrosion resistance, temperature limits, impact properties and code compliance for the actual service.
Manufacturing, inspection and documentation
SASA FLANGE can supply this product with identification linked to the raw-material heat. The agreed inspection and documentation plan is controlled by the purchase order.
Heat-number control and material certificate review.
Outside diameter, bore, thickness, web, facing and surface finish.
PMI, PT, UT, hardness or third-party inspection when specified.
EN 10204 3.1 MTC and ordered inspection reports.
RFQ checklist
- Material grade and specification
- Dimensional standard and edition
- Nominal size
- Quantity and destination
- MTC, NDE and third-party inspection requirements
- Pressure class
- Facing type and finish
- Mating flange details
Frequently asked questions
What should be included in an RFQ for a 316L spectacle blind flange?
State the material specification, dimensional standard and edition, size, pressure class or wall thickness, end or facing detail, quantity, inspection requirements and delivery destination.
Can a 316L spectacle blind flange be supplied with EN 10204 3.1 documentation?
Yes. EN 10204 3.1 material certification and heat-number traceability can be supplied. PMI, NDE, dimensional reporting or third-party inspection should be stated on the purchase order.
Is 316L suitable for every corrosive service?
No. Grade selection depends on the fluid chemistry, chloride level, temperature, pressure, fabrication route and governing design code. The project engineer should confirm service suitability.
Request a quotation
Send the standard, material, size, rating or wall thickness, quantity and inspection requirements for a technical and commercial review.
