The key dimensional parameters of steel pipes explained: “NPS”, “Schedule”, “Length” .
鋼管的關鍵尺寸參數解釋為：“NPS”、“計劃表”、“長度”。
The two key steel pipe sizes are the nominal pipe size (NPS) and wall thickness (WT):
兩個關鍵的導管尺寸是標稱導管尺寸（NPS）和壁厚（WT）：
·WT means “wall thickness”, i.e. the thickness of the pipe wall expressed in inches or millimeters. The higher the thickness of a pipe at a given NPS, the stronger the resistance of the pipe to the pressure of the fluid and its possible corrosion. The pipe thickness is called also “pipe schedule” (abbreviated, “SCH.”).
For a given NPS and schedule, the thickness of the pipe is fixed and defined in the applicable ASME standard B36.10 for carbon/alloy steel and ASME B36.19 for stainless and nickel alloy pipes)。
即導管壁的稠度，單位為英寸或毫米。在給定的NPS下，導管的稠度越高，導管對流體壓強的阻力及其可能的腐蝕越強。導管稠度也稱為“導管一覽表”（縮寫為“SCH”）。對于給定的NPS和明細表，導管的稠度是固定的，并在適用的ASME標準B36中定義。10適用于碳/合金鋼和ASME B36。19適用于不銹鋼和鎳合金管）
The term “NPS” replaced the previously used “Iron Pipe Size” (IPS) system, which was similarly used to designate the sizes of steel pipes. The term IPS referred to the approximate inside diameter of a pipe, expressed in inches (so a 4″ inches IPS pipe had an inside diameter of approximately 4 inches). Under the IPS system, pipes were manufactured with one wall thickness only (which was called “standard”, or “STD”): the outside diameter of the pipe resulted from the sum of the inside diameter and the wall thickness. With time, the petrochemical industry led to the introduction of additional wall thicknesses, like the “extra-strong” (XS or XH, i.e. “extra-heavy”), and the double-extra strong (XXS or XXH, i.e. double extra heavy).
術語“NPS”取代了以前使用的“糞能導管尺寸”（IPS）系統，該系統同樣用于指定鋼管的尺寸。術語IPS是指導管的近似內徑，單位為英寸（南方濤動4〃英寸IPS導管的內徑約為4英寸）。在IPS系統下，管道僅制造一個壁厚稠度（被叫為“標準”，或“性傳播疾病”）：導管的外徑由內徑和壁厚稠度得出。隨著時間的推移，石化行業引入了額外的壁厚，如“超強”（XS或XH，即“超重型”）和雙超重型（XXS或XXH，即雙超重型）。
Under the IPS system, and until the year 1927, manufacturers produced pipes in three thicknesses only. In the Thirties, ASME introduced a new system were pipes sizes were designated as we know them today (NPS). The NPS system showed some of the typical thicknesses existing under the IPS (STD, XS/XH, XXS/XXH) and introduced new ones (Sch. 5, 10, 20, 30, 40, 60, 80, 100, 120, 140, 160).
在IPS系統下，直到1927年，制造商只生產三種厚度的管道。在三十年代，美國機械工程師協會（ASME）引入了一種新的系統，即我們今天所知道的管道尺寸（NPS）。NPS系統顯示了IPS下存在的一些典型厚度（性傳播疾病、XS/XH、XXS/XXH），并引入了新的厚度（Sch.5、10、20、30、40、60、80、100、120、140、160）。
“NPS xx” designates a pipe size, but not an exact inside diameter of the pipe in inches: pipes with NPS under 12, have an outside diameter which is larger than the size designator (for example a pipe NPS 4 has an actual OD of 4 ”, i.e. 114.3 mm); for pipes above 14 inches, the outside diameter and the NPS match (for example, a pipe NPS 14 has an actual OD of 14″, i.e. 355.6 mm).
“NPSxx”表示導管尺寸，但不是導管的精確內徑（英寸）：NPS小于12的管道的外徑大于尺寸指示符（例如導管NPS4的實際光密度為4”，即114.3 mm）；對于大于14英寸的管道，外徑和NPS匹配（例如，導管NPS14的實際光密度為14〃，即355.6 mm）。
Pipes of a certain NPS have a constant outside diameter, but different inside diameters depending on the wall thickness (SCH): an NPS 6 pipe Sch. STD has the same OD of an NPS 6 pipe Sch. XXS, but a larger inside diameter (as the wall is smaller).
某些NPS的管道具有恒定的外徑，但不同的內徑取決于壁厚（SCH）：NPS6導管SCH。性傳播疾病具有與NPS6導管相同的光密度。XXS，但內徑較大（因為墻較?。?。
·“SRL” (“single random length”): means that the pipe has any random size between 5-7 meters; generally, pipes below 2 inches in diameter are manufactured with SRL, i.e. shorter (or half measures) of larger bore pipes（“單個隨機長度”）：表示導管的任意尺寸在5-7米之間；通常，直徑小于2英寸的管道采用SRL制造，即較短（或一半尺寸）的大口徑管道
·“DRL” (double random length): meaning that the pipe has any random size between 11-13 meters. Pipes above 2 inches in diameter are available in DRL size（雙隨機長度）：意味著導管具有11-13米之間的任意隨機尺寸。直徑大于2英寸的管道可采用DRL尺寸
·Cut Lengths: pipes are cut according to project specifications. Custom sizes are used to save welding costs at the installation site.管道根據項目規范進行切。定制尺寸用于節省安裝現場的焊接成本。
The term “random” refers to the fact that the pipe mill can control that the pipe length is between a min-max value, but cannot control the exact length of every single pipe (which will be variable, within the given range).
術語“隨機”是指導管工廠料袋指揮控制通信與情報系統導管長度在最小-最大價值觀之間，但不能指揮控制通信與情報系統每個導管的確切長度（在給定嶺內可變）。
A double random length pipe has an expected length twice the length of an SRL pipe.
雙隨機長度導管的預期長度是SRL導管長度的兩倍。
The term “pipe end” refers to how the pipe is finished at its extremities.
術語“導管末端”是指導管在其末端的完成方式。
·Plain ends (PE): plain ends are generally used for smaller diameters and require slip-on flanges and socket weld fittings. Plain ends are also common for stainless, duplex and nickel-alloy pipes（PE）：平原端通常用于較小直徑，需要滑動法蘭和承插焊接配件。不銹鋼管、雙相管和鎳合金管的平原端也很常見
·Beveled ends (BE): this is the most common pipe end type (beveled end pipes are joined by welding).（BE）：這是最常見的導管端部類型（斜端管道通過焊接連接）。
·Threaded ends (TE): threaded ends (which are generally NPT as per ASME B1.20.1 for petrochemical pipes) require threaded fittings and flanges and are used for smaller size pipelines or gas lines（TE）：螺紋端（根據ASME B1.20.1，石油化工管道通常為NPT）需要螺紋配件和法蘭，用于較小尺寸的管道或輸氣管線
·Threaded and coupled ends (T&C), generally used for gas distribution（睪酮和庫[侖]），通常用于天然氣概率分布
·Grooved ends (example Victaulic pipes): these are pipes that allow a quick connection, used for non-critical applications（例如Victaulic管道）：這些管道允許快速聯結，用于非關鍵應用
