Engineering English
Nominal Pipe Size (NPS)
Mechanical Engineering · Last updated: July 30, 2026 · How this entry was written
Definition: A dimensionless designator that corresponds to the diameter of a pipe, not equal to the actual outside diameter. It is used to standardize pipe dimensions across different schedules and materials.
Example in context
“The engineer specified a 6-inch Nominal Pipe Size for the main water line to ensure adequate flow capacity.”
“Mühendis, yeterli akış kapasitesini sağlamak için ana su hattı için 6 inç Nominal Boru Boyutu belirtti.”
Where engineers use it
Used when selecting pipe dimensions for a system. Engineers reference NPS to match flanges, fittings, and valves. It is essential for specifying pipe wall thickness via schedule numbers.
Synonyms: NPS, nominal diameter, pipe size
Practice: can you use “Nominal Pipe Size (NPS)” at work?
You are designing a cooling water piping system. How would you determine the appropriate Nominal Pipe Size for a given flow rate and allowable pressure drop?
Show a model answer
“Check the Nominal Pipe Size before ordering flanges and fittings.”
“Nominal Pipe Size (NPS)” in 21 languages
| English | Nominal Pipe Size (NPS) |
|---|---|
| Turkish | Nominal Boru Boyutu (NPS) |
| French | Taille nominale du tuyau (NPS) |
| German | Nennweite (DN) |
| Spanish | Tamaño nominal de tubería (NPS) |
| Chinese | 公称管道尺寸 (NPS) |
| Arabic | الحجم الاسمي للأنبوب (NPS) |
| Portuguese | Tamanho nominal do tubo (NPS) |
| Russian | Номинальный размер трубы (NPS) |
| Japanese | 公称管径 (NPS) |
| Italian | Diametro nominale del tubo (NPS) |
| Vietnamese | Kích thước ống danh nghĩa (NPS) |
| Hindi | नाममात्र पाइप आकार (NPS) |
| Thai | ขนาดท่อระบุ (NPS) |
| Indonesian | Ukuran Pipa Nominal (NPS) |
| Korean | 공칭 파이프 크기 (NPS) |
| Bengali | নামমাত্র পাইপ আকার (NPS) |
| Dutch | Nominale pijpmaat (NPS) |
| Swedish | Nominell rörstorlek (NPS) |
| Finnish | Nimellisputkikoko (NPS) |
| Ukrainian | Номінальний розмір труби (NPS) |
Frequently asked questions
What does Nominal Pipe Size (NPS) mean in engineering?
A dimensionless designator that corresponds to the diameter of a pipe, not equal to the actual outside diameter. It is used to standardize pipe dimensions across different schedules and materials. In Mechanical Engineering, the term carries a usage-frequency rating of 10/10 in the Engineering English library.
How do you pronounce Nominal Pipe Size (NPS)?
Nominal Pipe Size (NPS) is pronounced /ˈnɒmɪnəl paɪp saɪz/ (IPA). The Engineering English app plays audio for the term and checks your pronunciation with speech recognition.
How is Nominal Pipe Size (NPS) used in a sentence?
Example from an engineering context: “The engineer specified a 6-inch Nominal Pipe Size for the main water line to ensure adequate flow capacity.”
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