The following articles refute common fears and misconceptions regarding the use of PVC or other plastic pipe as part of a wood shop dust collection system. I found it very informative. I've used a combination of clear plastic tubing and "plumbing" PVC in my shop for over 20 years without incident (no grounding).Supporting KennyD's comment in 'MIG Welder Table - To Ground or Not to Ground?' --
"My Miller welding table in un-grounded, and will remain so. This reminds me of the dust collection threads on the woodworking forums-many say if you don't ground the plastic and metal pipe your shop will blow up."
"On PVC, static electricity, and the myth of home shop dust explosions"
Why dust explosions in a home woodshop are just a myth
Here's another, much more technical article with similar conclusions. (MYTHS are itemized at the very end.)
"Grounding PVC and Other Dust Collection Myths"
WoodCentral Articles & Reviews
There is a small risk of fire within the dust collector itself (from embers landing in the bin or bag), but there's no need to worry about the plastic pipes. It's hard to believe there's so much hype about grounding them.