Langfang Zhengyuan Chemicals Co., Ltd.


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A.General introduction of the Products
Pipeline conveying is a most effective conveying method of such medium as water,gas and petrolium, The reliability of pipenlines depends,to the great extend,on the anti-corrosion of the steel pipelines.The life of the pipelines may extend decades by adopting a fine cotaing method.ZHENG YUAN heavy-duty powder coatings is a ideal anti-corrosion material of easy coatings and rapid curing.The products of EPY₂ series (I-IV)is suitable for the coatings of single layer coatings pipelines and compound coating pipelines for oil and gas;oil-field drill pipes,water-flooding pipes,city water-pipes,sewage pipelines,reinforcing bars and auto engine parts.

EPY₂-I heavy duty anti-corrosion powder coating has the following good specific properties:
A. The coatings can resist chemical corrosion by such organic matters in the conveyed medium as H₂S,CO₂,O₂,acid,alkali,and salt,and can resist corrsion by underground salty water,sea water and various organic acid produced by microorganism in the soil.
B. The coating is tough and wear-resisting;and can resist mechanical damage in construction and stress damage by plant roots and the soil,with its fine impact resistance and bending resistance.
C. The coating,with pretty high insulation resistance,can resist chemical corrosion under the cathode pretection so as to achieve the result to safeguard the coated for a long period of time.
D. The coating has good high temperature resistance and low temperature resistance with the range between -30^oC and 90^oC,EPY₂-III powder coatings can be used at the temperature as high as 160^oC.
E. The powder coating is suitable for high efficient assembly line with its simply working process and rapid curing and the workpiece doesn't need priming paint.
F. The coating quality is easy to control and the pipe surface easy to be checked and repaired.

II Varieties and Properties:
ZHENG YUAN heavy duty modified epoxy powder coatings can be divided into EPY₂-I. EPY₂-II. EPY₂-III and EPY₂-IV,according to the curing time and the applying specific properties.Each has its own advantages and applying fields.

Items Varieties Index		EPY₂-I	EPY₂-II	EPY₂-III	EPY₂-IV
GellingTime	180^oC	100~150	23~25	35~45	30~35
	205^oC	70~90	17~19	25~30	23~28
	230^oC	40~50	5~10	15~18	14~16
Curing Time (min)	180^oC	10~15	4	8	6
	205^oC	8~10	2	4	2.5
	230^oC	5~7	1	2	1
Applying Scope		Pipe inside spraying coating auto engine and flange,elbow,valve etc.special shaped parts.	Pipe outside coating,spirial reinforcing bar,long distance pipelines burried underground	Pipe inside and outside coating auto engines and special shaped parts	Three-layer structure anticorrosion prmer or pipe outside spraying coating
Distinguishing features		1. Slow curing 2. Good flow 3. Good heat resistance 4. Fine gasoline resistance 5. Nonpoisonous to be used on water pipes. 6. Baked at later stage	1. Rapid reaction and curing speed with extra heat 2. Good mechanical 3. Huminity resistance used in the range of -40~90^oC 4. High working efficency	1. Mid-curing speed 2. Low melting viscosity to get even smooth film surface 3. Good high temperature resistance to be used on the drilling pipes in oil fields 4. Give consideration of flow and curing speed 5 Not so good storage	1. High activation at high temperature 2. Good adhesion on steel 3. Long gelling time to be good to mid gelling layer melting 4. Good affinity with copolymers of ethylene and vinyle acetate

Powder Indes for Heavy -duty Anti corrosion Powder coatings

No.	Items	Unit	Test method	EPY₂-I	EPY₂-II	EPY₂-III	EPY₂-IV
1	Size	um	GB6554	<150um average size40~50um
2	Density	g/cm³	GB4472-86	1.3~15
3	Nonvolatile content	%	GB6554-8	>99.5
4	Curing curve	___	Q/GD0151.2-93	____
5	Magnetic content	%	GB2482-83	<0.002

The Coating Property

No.	Items	Unit	Standard	Index
No.	Items	Unit	Standard	EPY₂-I	EPY₂-II	EPY₂-III	EPY₂-IV
1	Adhesion	Grade	Q/GD0151.5-93	1	1	1	1
2	Bending Resistance	Grade	Q/GD0151.6-93	1	1	1	___
3	Impact Resistance	J	Q/GD0151.7-93	20	23.4	20	___
4	Wearing Resistance	L/um	Q/GD0151.8-93	3.0	3.0	3.0	___
5	Insulation Resistance	.m²	Q/GD0151.9-93	>1*10⁸			___
6	Cathodic Disbonding 48h,65^oC	mm	Q/GD0151.10-93	8 Film thickness35050um			<8 60-80um
7	10%HCL Solution Immersing	90Days	Q/GD0151.11-93	The coating having no change			___
8	10%NaCL +H₂SO₄ PH=3	90Days	Q/GD0151.11-93	The coating having no change			___
9	10%NaCL	90Days	Q/GD0151.11-93	Ditto			___
10	5%NaOH	90Days	Q/GD0151.11-93	Ditto			___
11	Distilled Water Immersion	90Days	Q/GD0151.11-93	Ditto			___

III.Working Method:

A.Woking Process:
Electrostatic spraying or direct scatter homogeneously on the preheated pipe walls pretreated by cleaning rust of greasy dirt or sand blasting;and then melting,curing,interlinking and flowing at the given temperature so as to form homogeneous,and fine coating film fast adhesive to the walls.
Single Layer Coating Process:
Storage outside pipes

High temperature burning

Pills(or sand blasting)

Preheating pipes

Coating

Cooling

Testing

Repairing and mending

Finished products
Compound structure coating is much similar to single layer coating in technology requirements with some defferences in coating stage,The coating process is as follows:
Storage outside pipes

High temperature burning

Pills or sand blasting

Preheating pipes

Coating

Sided to bind gum tape

Sided to bind polyethylene

Cooling

Tesing

Finished products

B.Working Proccess Instructions:
1. High temperature burning means to burn the pipe surface with blowlamp so as to eliminate for eigh things or greasy dirts,and to loosen rust in order to get rid of it easily
2. Sandblasting(or pillblasting) aims at improving adhesion between workpieces and coatings. The anchor lines produced by sand blasting must be 30~75um at depth.The workpiece must be cleared before coated.
3. According to the specific working conditions,intermediate frequency induction heating,oil-burningheating,or air heating can be adopted.The heating tempereture can be 200~250^oC,in general,depending on the coating thickness,pipe wall thickness and/or ambient temperature.To avoid metal oxidation,the pipes mustn't be preteated at more than 260^oC.
4. The single layer anti-corrosion epoxy coating thickness is better at 350

50um,with single spraying to reach the required thickness.Repeated spraying on the same length of the pipe must be forbidden to avoid unuiformness within the coatings,and affecting flow and anti-corrosion.
5. As EPY₂-I,if preheating can't achieve complete curing,later-stage baking must be adopted.As for EPY₂-II and EPY₂-III,consideration must be taken to later stage baking so as to achieve complitely curing,according to the thickness of the pipe walls.
6. As for EPY₂-IV,three-layer anti-corrosion coating thickness is better at 60-80um.At the powder gelling process,adhesive is painted on the coatings to make the epoxy coating and adhesive melt and cure into a whole on the interface.And lastly polyethylene tape is slantly binded on the pipes to fast combing with gum coating by hard rolling.
7. Electric spark leak test must be made after curing,with the testing voltage of 5v/um,Single layer coating voltage mustn't be less than 2000v,and three-layer anti corrosion structure mustn't be smaller than 25 kilovolt.

C.The Film Joint and Leakage Mending:
The welded part of the pipes joint can be mended with various methods after pill blasting proccess,eg.the two pqrts epoxy system without solvent,the adhesive tape of PE type,or the heat-contracting cover(not used in the high-temperture area)and powder coating has been adopted widly,even mending the broad bore pipe inside wall too,robot move along the pipe,blasting automaticly and spraying powder,the powder gets completely cured,relying on the induction heating to make the pipe inside and outside mending completed at the same time.The film joints of the three layer anti-corrosion structure are generally are installed with the heat-contracting cover or PE type radiating intertlinkage.

When the leakage is found out by the electric spark review,it should be mended in time.The single layer leakage mending of the fusibility epoxy powder coating can be achieved by two parts liquid epoxy system without solvent.The finished product pipes must be tested according to the qulity control standard beforeit can be put into use.