1 http://www.answers.com/pipe%20vs%20tube→WikiAnswers的解释

A pipe is a tube. Tube is a shape. Pipe is the type of tube it is. A tube can be plastic, paper, wood, etc.

(Pipe就是Tube，但Tube意在“管型”结构(中空的)，Pipe意在“管为”原义(导流的)。Tube可以是塑料制、纸制、木制等)

2 http://www.bicyclesports.us/id198.htm的解释

The difference between a pipe and a tube is how they are measured, and ultimately what they are used for.

(pipe和tube的区别表面在于它们的大小标称，而实际在于它们的用途)

     A pipe is a vessel - a tube is structural. (pipe是容液的—“管为”原义，tube是结构性的—“管型”结构)

     A pipe is measured ID - a tube is measured OD. (pipe以内径标称大小，tube以外径标称大小)

     How they are measured...  Pipes are measured ID or inside diameter because they are vessels.  Tubes are measured OD or outside diameter because they are structural.

3 http://www.diygokarts.com/articles/pipe-vs-tube.html的解释

Round pipe is commonly available even at your local hardware store. Tubing is available at your metal supplier.

Tube is called out by the outside diameter (OD). A 1" round tubing will be exactly 1".

Pipe is called out by its inside diameter rather than its outside diameter. A 1" pipe will measure 1.315" OD.

4 http://www.answers.com/Water_pipe→Wikipedia的解释

Pipe is usually rigid and is supplied in straight lengths. Tubing is either rigid and straight, or is flexible and supplied in rolls. Water pipe is measured by its Nominal Pipe Size (NPS). Pipe in other industries is also measured by its NPS, while tubing is described by its nominal diameter which is typically neither its actual inside or outside diameter. Soft-temper copper tubing, used for air conditioning and refrigeration ('ACR'), is described by its actual outside diameter, however.

5 《ASME B36.10 Welded and Seamless Wrought Steel Pipe》标准的解释

This Standard covers the standardization of dimensions of welded and seamless wrought^注 steel pipe for high or low temperatures and pressures.

The word pipe is used, as distinguished from tube, to apply to tubular products of dimensions commonly used for pipeline and piping systems. Pipe NPS 12 (DN 300) and smaller have outside diameters numerically larger than their corresponding sizes. In contrast, the outside diameters of tubes are numerically identical to the size number for all sizes.

    本标准规定内规管的尺寸，适用于高温高压或低温低压用已作钢制焊接与无缝管。

    内规管(pipe)，与外规管(tube)所指不同，指普通管线(pipeline)和管系(piping system)用管。公称内径管规格NPS(Nominal Pipe Size)不大于12吋(DN 300)的内规管的外径尺寸数字大于对应的管规格数字。与此相反，所有规格的外规管的外径数字等于对应的管规格数字。

注：Wrought, work的一种过去式和过去分词，用作现代金属原材料分类形容词时，Unwrought(未经任何再变形制作过的)，相当于Cast(浇铸的)，指铸造的(坯料，第1类金属原材料)； Wrought(经过再变形制作过的)，指一切经过再变形制作的非原始浇铸的(材料，第2类金属原材料，如棒、板、管、型材、锻件等)；实际上，世界上只有这两类金属原材料，但至今，还未能正式引进中文，例如，在下列一类标准使用中就显得乱七八糟的：

ASME B16.9 Factory-Made Wrought Buttwelding Fittings (已作料批制对焊端管件)

ASME B16.28 Wrought Steel Buttwelding Short Radius Elbows and Returns (已作钢制短径对焊弯通和回通)

ASME B16.50 Wrought Copper and Copper Alloy Braze-Joint Pressure Fittings (已作铜及铜合金制铜焊端压力管件)

ASME B36.10 Welded and Seamless Wrought Steel Pipe (已作钢制焊接与无缝内规管)

EN 12165 Copper and copper alloys — Wrought and unwrought forging stock (铜及铜合金  锻造用已作和未作料)

MSS SP43 Wrought Stainless Steel Butt-Welding Fittings (已作不锈钢制对焊端管件)

MSS SP75 Specification for High-Test, Wrought, Butt-Welding Fittings (已作料制高压对焊端管件)