What kind of underground pipe do you use for natural gas grill?

For natural gas grills, you should use polyethylene (PE) pipes. These pipes are specifically designed for natural gas distribution and are highly durable, flexible, and resistant to corrosion. They are also relatively easy to install and can withstand the high pressure of natural gas. Polyethylene pipes come in different diameters and lengths, so you can choose the one that best suits your requirements.

It's important to note that installing underground gas pipes requires specialized knowledge and expertise, so it's always recommended to consult with a professional plumber or gas fitter to ensure proper installation and safety compliance.