Bronze female cap (B108) and male plug (B109), NPT — class 125
TECTUL · Dispatch across Colombia · Exports to Central & South America
A pair of complementary brass bronze parts for NPT thread blanking: the female cap (B108) covers an already-installed male-threaded end, and the male plug (B109) blocks a female-threaded port. They are used to take a manifold, equipment or network outlet out of service temporarily or permanently, or to blank a test/spare port. They share material, thread standard and pressure rating with the rest of the class 125 threaded bronze line; no manufacturer dimensional sheet was located for either, so exact dimensions are confirmed on quotation.
Important: Before using these data in engineering, design or installation decisions on systems exposed to mechanical, pressure, rupture, fatigue, impact or water-hammer risk, it is essential to read the technical notice and limitation of liability at the end of this sheet.
SKU VT-59154 (B108 female cap) and VT-59155 (B109 male plug) · 1/8″–1/2″ range · sold by the unit
1. Technical specifications
| B108 — Female cap | Female NPT thread; screws over an already-installed male end to close it |
| B109 — Male plug | Male NPT thread, hex or square head for a wrench; screws into a female port to close it |
| Material (both) | Cast brass bronze |
| Thread (both) | NPT per ANSI/ASME B1.20.1 |
| Pressure rating (both) | Class 125 (ASME B16.15): 200 psi (13.8 bar) ≤66 °C with water/oil/non-flammable gas · 125 psi saturated steam |
| Commercial range (both) | 1/8″, 1/4″, 3/8″, 1/2″ NPT |
| Dimensions (length, wrench width, weight) | Confirmed on quotation — no manufacturer dimensional sheet was located for either reference |
| Applicable standards | ASME B16.15 · ANSI/ASME B1.20.1 |
Do not confuse the female cap (B108, to cover an existing MALE end) with the male plug (B109, to blank an existing FEMALE port): the blanking piece's thread is always the opposite of the end being blanked.
2. Frequently asked questions
Which part do I need to blank a leftover female NPT outlet on a manifold?
The B109 male plug: its male thread screws directly into the female port to close it.
And to blank a male end, for example an already-installed nipple?
The B108 female cap: it screws over the male end.
Why is there no dimensional table?
No manufacturer dimensional sheet was located for either reference; exact dimensions (length, wrench width, weight) are confirmed on quotation with the supplier.
Are they suitable for pressurizing a hydrostatic test line?
Within their 200 psi (13.8 bar) cold rating, yes; for higher test pressures, confirm with the supplier whether a higher-rated reference exists.
3. Application notes
Feasibility
Suitable for temporary or permanent blanking of NPT ports in water, compressed air and low-pressure oil. Do not specify without first confirming exact dimensions with the supplier, since no manufacturer dimensional sheet is available.
Installation
Seal the thread with PTFE tape or a fluid-compatible sealant before threading. Tighten with a wrench on the head's hex/square (plug) or the body (cap), never on the fitting it connects to. Do not exceed the recommended torque: bronze is softer than steel.
Design
Rating valid cold (≤66 °C); for steam, 125 psi. Confirm exact dimensions with the supplier before detailing installation drawings. Do not use these parts as shutoff valves: they are fixed blanks, with no way to reopen the passage without unthreading them.
4. Technical notice and limitation of liability
The pressures, dimensions, weights and other characteristics in this sheet are theoretical calculation values obtained from nominal properties published in the standards cited (ASME B36.10-2022, ASME B31.3-2024, ASTM A106/A106M-19a, ASTM A53/A53M-24, API Spec 5L 46th ed.). They guide selection; they are not a certificate of conformity for any given lot.
The actual behavior of each lot varies with manufacturing — wall tolerance (up to −12.5%), out-of-roundness, residual stresses — and with the raw material — chemical composition within the ranges the standard allows, heat-to-heat differences. To certify a lot, the tests defined by its product standard are required: tensile test, flattening test and hydrostatic test, documented in the manufacturer's mill test certificate (MTC), which TECTUL supplies upon request; testing of the lot in an independent laboratory can also be arranged.
These values must not be used as the sole criterion in critical or safety applications, or wherever failure of the line may compromise people, property or the environment: in such cases the design belongs to the project's responsible engineer under the applicable code (ASME B31.3, B31.1 or the one governing the installation), with the design temperature, corrosion allowance and load cases of the actual service. Before deciding with these data, consult our technical team.
Sources
- ASME B16.15-2020 — Cast Bronze Threaded Fittings: Classes 125 and 250
- ANSI/ASME B1.20.1-2013 (R2018) — Pipe Threads, General Purpose, Inch (rosca NPT)
- Página de producto TECTUL "B108 - Tapa Hembra Bronce" (SKU VT-59154) y "B109 - Tapón Macho Bronce" (SKU VT-59155), previews/conduccion-de-fluidos/racores-y-acoples/: rango comercial 1/8″–1/2″ y función de cada pieza
This data sheet is the property of TECTUL, part of the Industrias IMR group. Reproduction without attribution is prohibited. Original document and updates: tectul.com/en/conduccion-de-fluidos/racores-y-acoples/ficha-tecnica-b108-tapa-hembra-bronce.