How many days can cng cylinders be inspected in advance?

Cng cylinders can be reviewed 30 days in advance. The expiration inspection of gas cylinders needs to be applied one month in advance. The annual inspection time of CNG cylinders is different in different regions. CNG cylinders are not inspected three years before installation, and the latter needs annual inspection. The service life of CNG cylinders can reach 15 years, and most operating vehicles need to be scrapped within 10 years.