LPG cylinder powder coating: process, durability and brand colours

The paint colour is the first thing customers see on a gas cylinder, and it is also the layer that protects the steel from rust through many years in circulation. LPG cylinder powder coating is the technology widely used by manufacturers because the coating is thick, even, firmly bonded and more impact resistant than wet paint. This article explains the process, how to check coating quality and what dealers need to prepare when ordering a custom colour for their brand.

What is powder coating?

Powder coating uses dry paint powder instead of liquid paint. The spray gun gives the powder particles an electrostatic charge while the cylinder is earthed; the electrostatic attraction pulls the powder evenly onto every surface, including hidden areas. The cylinder then passes through a curing oven, where the powder melts and hardens into a continuous, hard and glossy film.

Compared with traditional wet paint, powder coating offers these advantages:

• A thick, even coating with fewer runs and air bubbles.
• Good adhesion and impact resistance — important for cylinders that are rolled, stacked and loaded every day.
• Better rust protection when the steel surface is properly prepared before coating.
• No solvents, and overspray powder can be recovered, making it better for the working environment.

The LPG cylinder powder coating process

1. Surface cleaning: after welding and pressure testing, the cylinder is shot blasted (with steel shot) to remove rust, mill scale and grease and to create a rough profile that helps the coating bond firmly. This step determines how durable the coating will be.
2. Powder spraying: in an enclosed spray booth, electrostatic guns coat the body, the domes and the handle of the cylinder.
3. Curing: the cylinder passes through a curing oven at the temperature and time recommended by the powder manufacturer (typically about 180 – 200°C).
4. Cooling and inspection: coating thickness is measured, and adhesion, colour and surface finish are checked.
5. Branding: the logo, brand name and mandatory information are printed on the cylinder body by screen printing or with heat-resistant, scratch-resistant decals.

See every stage from blank cutting to dispatch on our LPG cylinder manufacturing process page.

Checking coating quality

• Coating thickness: measured with a thickness gauge at several points on the body and domes.
• Adhesion: a cross-cut test — score a grid of squares, apply adhesive tape, pull it off and look at how much coating comes away.
• Colour: compared with the approved colour sample under the same lighting.
• Surface: no pinholes, no bubbles, no exposed steel and no powder runs at the edges of the handle and foot ring.

When receiving a new batch of cylinders, dealers should also check for scratches caused in transport — see 7 checks for a compliant LPG cylinder.

Choosing colours and printing logos for your own brand

For OEM / ODM / OBM cylinders, the paint colour is the dealer’s brand identity in the market. A few points to note:

• Provide a specific colour code (a RAL or Pantone code) rather than a description such as “dark green” or “bright red”, to avoid colour differences between batches.
• Approve a sample cylinder before mass production, and keep one sample to compare against later batches.
• Choose a colour that stands out from other brands in your area, so customers recognise your cylinders and fewer of them are retained by others.
• Keep the logo simple, with good contrast against the paint colour so it prints sharply and lasts.
• Check current regulations on labelling and mandatory information on cylinders before finalising the design.

For details on documents, quantities and lead times when ordering, read what to prepare when ordering private-label LPG cylinders.

Frequently asked questions

Written by the VietnhatGas technical and sales team — a batch manufacturer of LPG cylinders. This content is for reference; regulations and standards may change, so please check the current texts.