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What Is a Square Plug (SQ)?

A SQUARE PLUG (SQ) is a solid threaded fitting used to seal the open end of a pipe, port, or fitting body. The square head provides wrench engagement for secure installation and removal — a practical feature wherever the closure may need periodic access during maintenance. HEBEI JIUYUAN PIPELINE MANUFACTURING CO.,LTD . lists this fitting under its standard threaded product range.

Key Selection Criteria

Before specifying a square plug for your system, confirm the following criteria against your application requirements.

1. Nominal Pipe Size Match

The fitting must match the nominal thread size of the port it seals. The range available covers:

| Nominal Size | |---| | 1/8" | | 1/4" | | 3/8" | | 1/2" | | 3/4" | | 1" | | 1-1/4" | | 1-1/2" | | 2" | | 2-1/2" | | 3" | | 4" |

Always verify the thread size on the receiving fitting or port before ordering. A size mismatch will prevent a proper seal.

2. F and G Dimensional Parameters

Two key dimensions are published for each size:

• F — the width across the flats of the square head (mm), which determines the required wrench size.
• G — the thread engagement length (mm), which affects sealing depth and required torque.

Dimensional reference table (mm):

Buyer note: These values are drawn from the published product data. Confirm final dimensions with the supplier at inquiry, as manufacturing tolerances and the applicable execution standard may affect supplied dimensions.

3. Thread Type and Execution Standard

Confirm that the thread form required by your system — for example NPT, BSPT, or another form — matches the plug offered. The published product excerpt does not specify a thread form; buyers should state their requirement when inquiring. HEBEI JIUYUAN PIPELINE MANUFACTURING CO.,LTD . references execution standards including GB, ANSI/ASME, JIS, and DIN across its product line. Confirm which standard applies to your order.

4. Material for the Intended Service

The published listing does not specify material grades for this fitting. The company works with carbon steel, alloy steel, and stainless steel across its threaded product range. Specify the material grade that suits your service fluid, operating temperature, pressure, and corrosion requirements, and confirm availability when placing an inquiry.

5. Application Fit and Service Conditions

Threaded square plugs are sealing components, not flow-control devices. They are suited to closing off ports, test connections, instrument taps, and unused outlets on manifolds, valves, and fittings. Before specifying this fitting, confirm:

• The plug is not intended for throttling or flow regulation.
• No special end-use certification (such as fire-safe, CRN, or NACE) is required, unless confirmed as available.

SQUARE PLUG (SQ) vs. Square Head Plug

HEBEI JIUYUAN PIPELINE MANUFACTURING CO.,LTD . also lists a Square Head Plug separately in its catalog. The available published data for that product does not include dimensional details beyond the catalog entry. Buyers who require detailed size and dimension confirmation should reference the dimensional table above and clarify which catalog entry applies to their specification when contacting the supplier.

Specification Checklist Before Ordering

Submit the following information when contacting HEBEI JIUYUAN PIPELINE MANUFACTURING CO.,LTD .:

• Nominal size — from 1/8" to 4" per the published range
• F dimension reviewed — confirm against available wrench size or torque requirement
• G dimension reviewed — confirm adequacy for port depth
• Thread type — NPT, BSPT, or other as required
• Material grade — carbon steel, alloy steel, or stainless steel as required
• Service conditions — pressure, temperature, and fluid type
• Applicable standard — GB, ANSI/ASME, JIS, DIN, or other

When This Fitting May Not Be Suitable

A threaded square plug does not apply when:

• A hex head plug is required for installations with limited wrench clearance.
• The port uses a flanged or socket-weld end connection rather than a threaded port.
• A pipe cap or blind flange is needed at the pipe end rather than a port closure.
• Special material certifications or documentation beyond standard supply are required and have not been confirmed as available.

Summary

The SQUARE PLUG (SQ) is a threaded sealing fitting available from HEBEI JIUYUAN PIPELINE MANUFACTURING CO.,LTD . in nominal sizes from 1/8" to 4". Selecting the right size means matching the nominal thread, reviewing the published F and G dimensions against your tooling and port requirements, and confirming thread type, material grade, and service conditions with the supplier. No pressure ratings, certifications, or delivery commitments are stated in available published materials; buyers should request these details directly.