What Is the Difference Between Spectacle Blind and Spade in Piping Systems?

In the world of industrial piping, isolation devices are critical for safe maintenance, inspection, or shutdown of systems transporting high-pressure or hazardous fluids. Among these devices, spectacle blinds and spades (also known as line blanks) are widely used in oil & gas, petrochemical, and offshore installations. Though they serve a similar function—flow isolation—their design and applications differ in meaningful ways.

In this article, we’ll compare spectacle blinds vs. spades, explore their functional differences, and provide insight into how to choose the right one for your project.

What Is a Spectacle Blind?

A spectacle blind is a dual-purpose isolation device consisting of two discs:

One is a solid plate (blind) for complete flow shut-off.

The other is a ring spacer with an open center, allowing fluid flow.

These two discs are permanently connected by a web or a handle, resembling a pair of spectacles—hence the name.

Key characteristics:

Standard: ASME B16.48

Material Options: Carbon steel, stainless steel (e.g., ASTM A240 316/316L), alloy steel, nickel alloys (e.g., Inconel 625)

Common Pressure Ratings: 150#, 300#, 600# and above

Usage: Installed between two flanges, typically with long stud bolts to accommodate the combined thickness

Advantages:

Easy switching between open and closed positions by rotating the unit

Remains in-line at all times—no loose parts

Minimal risk of misplacement or installation error

What Is a Spade?

A spade or single-blind flange is a solid disc designed to block flow entirely. Unlike a spectacle blind, a spade is a standalone piece. When flow is required, it can be removed and replaced with a spacer ring of the same thickness.

Key characteristics:

Standard: Also ASME B16.48

Material: Typically the same as piping or flange materials (e.g., stainless steel ASTM A240 316/316L)

Marking: Usually includes a handle with a color code to indicate “blind” or “open”

Applications:

Ideal for large diameter or heavy pipeline systems where rotating a spectacle blind would be impractical due to weight

Used in systems requiring temporary or infrequent isolation.

Spectacle Blind vs. Spade: Key Differences

Feature	Spectacle Blind	Spade (Line Blank)
Structure	Two discs joined by a bridge	Single solid plate with handle
Isolation Function	Can rotate between blind and open positions	Must be manually removed and replaced
Use Case	Frequent or semi-permanent isolation	Infrequent isolation or high-weight systems
Installation	Remains in-line, rotates to desired position	Needs disassembly and reassembly
Ideal for	Small to medium size pipelines	Large or high-pressure pipelines

How to Choose Between a Spectacle Blind and a Spade

The decision depends on factors such as:

Frequency of isolation operations

Frequent switching = Spectacle Blind

Infrequent switching = Spade + Spacer

Pipeline size and weight

Small/medium = Spectacle Blind

Large/heavy = Spade is easier to handle

Space constraints and installation time

In critical piping systems, both options offer reliable positive isolation that satisfies global safety standards. Whether you choose a spectacle blind or a spade, ensure the item is manufactured per ASME B16.48, and materials comply with standards such as ASTM A240, ASTM A182, or ASTM B564 depending on the application.

Haihao Group – Your Reliable Supplier for Spectacle Blinds and Spades

At Haihao Group, we manufacture and supply a complete range of spectacle blinds, spades, and ring spacers in materials such as:

• Stainless Steel ASTM A240 316/316L
• Nickel Alloys (e.g., Inconel 625 – UNS N06625)
• Carbon & Alloy Steel

All products conform to ASME B16.48 and are delivered with EN 10204 3.1 certification, ensuring material traceability and quality compliance. Our components are widely used in offshore, petrochemical, and pipeline projects worldwide, including recent exports to Singapore, Ivory Coast, and the Middle East.

Contact Us for Your Isolation Fitting Needs

Need customized spectacle blinds or spades for your next pipeline or maintenance project?

Reach out to Haihao Group for technical support, pricing, and fast delivery.