HDG Seamless Welded Pipes Hot Dipped Galvanized With PE BE BSPT NPT

Hot Dipped Galvanized HDG Seamless Or Welded Pipes With PE BE BSPT NPT

Hot-dip galvanizing (HDG) pipes , as referenced is the process of dipping fabricated steel into a kettle or vat of molten zinc.
Hot-dip galvanizing (HDG) is the process of coating on steel materials with a layer of zinc.
Typical galvanized coatings range from 3-8 mils (75-200 mi- crons) thick. When designing and detailing tapped holes,
the increased thickness is important. Best practice suggests that the hole be tapped after galvanizing, removing the coating on the interior mating surface.

Advantage of Hot .Dipped  Galvanzied.

1. Lower first cost. Hot dip galvanizing generally has the lowest first cost when compared to other commonly specified comparable protective
coatings for steel. The application cost of labour intensive coatings such as painting has risen far more than the cost of factory applied hot dip galvanizing.

2. Lower maintenance / lower long term cost. Even in cases where the initial cost of hot dip galvanizing is higher than alternative coatings, galvanizing is
invariably more cost effective, due to lower maintenance costs during a longer service life. Maintenance is even more costly when structures are located in
remote areas. Maintenance programmes also invariably have a negative impact on productivity.

3. Long life. The life expectancy of hot dip galvanized coatings on structural members is in excess of 50 years in most rural environments, and between
10 to 30 years in most corrosive urban and coastal environments.

4. Surface preparation. Immersion in acid ensures uniform cleaning of the steel surfaces, in contrast organic coatings must be applied on abrasive blast cleaned
surfaces (generally to ISO 8501 - 1 to SA 2) and verified by third party inspection. Additionally, the application of organic coatings is limited in terms of prevailing
ambient temperature and relative humidity. This adds to the cost of applying a heavy duty paint system.

5. Adhesion. The hot dip galvanized coating is metallurgically bonded to the steel surface.

6. Environmentally friendly. The coating is not toxic, arid it does not contain volatile substances.

7. Speed of coating application. A full protective coating can be applied in minutes, a comparable multicoat paint system, may require up to a week.
The effective application of a hot dip galvanized coating is not influenced by weather conditions.

Product Information/Basis Information/Specification

Technology/ Technical Data Sheets

Thickness List for seamless pipes as per ANSI B36.10

Unit: MM

Dimension Design

OD … Outside Diameter

ID … Inside Diameter

WT … Wall Thickness

L … Length

If minimum wall thickness is required variations are allowed on the plus side only

Butt Welding Ends

ANSI / ASME B16.25-2007

Fig. 4 Weld Bevel Details for GTAW Root Pass [WT > 3mm (0,12 in.) to 10mm (0,38 in.), Inclusive]

GENERAL NOTES:

a) This detail applies for gas tungsten arc welding (GTAW) of the root pass where nominal thickness is over 3mm

b) Linear dimensions are in millimeters with inch values in parentheses.

Straightness Requirement 

tandard pipes and tubes are supplied straightened to the eye: for special applications the

permissible deviation from the straight line may be agreed between purchaser and pipe

manufacturer; the maximum permissible deviation from the straight line related

to the length of measurement L is to be indicated, e.g. 1mm/1000mm.

Eccentricity

E is half of the difference between biggest and smallest

wall thickness (WT) values in one cross section.  

In terms of mm:

However, eccentricity is expressed as a percentage of the mean wall thickness of this cross section

Mean Diameter inside and outside 

D0 is the arithmetic mean between the smallest and biggest tube diameter on any one pipes or tube

circumference. If minimum wall thickness is required variations are allowed on the plus side only

Ovality

O is the difference between biggest and smallest diameter on any one tube circumference

As a percentage of the mean diameter this is:

Ovality must not be confused with eccentricity.

Galvanzied  PROCESS

FAQ: Question and Answers 

Q: What is the different between seamless pipes and seamless Tubes?

A: Seamless steel pipes shall not be confused with seamless tubes. Indeed, there are a few important differences between pipes and tubes, which are not only semantic. In general, the word “pipe” applies to any tubular used to convey fluids, whereas the word “tube” applies to tubular sections (of various shapes, round, oval, squared) used for structural/mechanical applications, instrumentation systems, and the construction of pressure equipment like boilers, heat exchangers, and superheaters.

Q: What is the tolerance of the seamless pipes

A: Dimensions tolerance for API 5L /A106GR.B seamless pipe.

1. For outer diameters less than 2 3/8 in (60.3 mm), pipe body diameter tolerance +/-0.5 mm. Pipe end +/- 0.5 mm; Out of Roundness tolerance for pipe body is 0.9 mm (0.036 in), pipe end 0.6 mm (0.024 mm).

2. For OD equal or above 2 3/8 in (60.3) to 24 in (610 mm), (diameter tolerance) for pipe body is +/- 0.0075D,pipe end +/- 0.005D but max to +/-1.6 mm (0.063mm);

Roundness tolerance for pipe body≤0.015D, pipe end≤0.01D.

(In case agreed with manufacturer and client, more strictly tolerances could be applied)

3. For wall thickness

Below than 4 mm (0 0157 in), tolerance +0.6 (0.024 mm), -0.5 mm (0.020 in);

For API 5L seamless steel pipe thickness in 4 mm to 10 mm (0.394 in), +0. 150t, -0.125t;

For API seamless pipe thickness 10 mm to 25mm (0.984 in), +/-0.125t;

Wall thickness≥25 mm, +3.7mm or +0.1t (if larger) and -3.0 mm (0.120 in) or -0.1t (if larger).

t for thickness,

4. For straightness, max for full length, tolerance maximum 0.15% of length.

5. Straightness, max deviation for pipe end, shall be≤0.3 mm /m.

6. Length +/- 200 mm for general, +/- 25.4 mm for special.