To get a good seal, when cutting my 18 corrugated pipe: Do I need to cut @ the outside or inside of corrugation? or does it not matter?

Not exactly sure what is meant by the inside or outside of the corrugation, but you want to cut the pipe as straight as possible to have the best seal with the lid.

Are these flat Like other sizes also?

I believe you could call it flat. Around the rim are holes for hold down screws. I used a few but I don't think they are necessary. My cover is 6" down and I have driven my tractor over the top soil many times,so it is durable.

Will this fit a norwesco 24 in by 20 in manhole extension?

This cover is designed to fit corrugated pipe with an inside diameter of 18". I would recommend looking at the technical drawing for this product on the manufacturers website to determine if it would fit your application: https://www.polylok.com/mwdownloads/download/link/id/320/ Seeing that this covers OD is only 20.57" I would say no to your question.

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Polylok 18" Heavy Duty Cover/Lid for Corrugated Pipe (PN: 3007-HDC)

Product ID: 93591982

Details

Material
High Density
Color
Green
Brand
Polylok
Style
Compact
Product Dimensions
21"L x 21"W

🔒Airtight seal

☀️UV protection

🛡️Heavy-duty design

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NZ$224

Duties & taxes included

In stock

Sold byAmazon New ZealandDelivered byDesertcartCustomer service byDesertcartReturns14 days · 30 with PRO

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Description

🔧 Lock it down with style!

PERFECT FIT - Designed specifically for 18" corrugated or ribbed pipes, ensuring a snug and reliable fit.
SECURE YOUR SPACE - Includes square drive screws to prevent unauthorized access, keeping your area safe.
ULTIMATE PROTECTION - Features a skid-resistant surface and top-tier UV protection to withstand the elements.
UNMATCHED DURABILITY - Crafted from High Density Polyethylene (HDPE) for long-lasting performance.
EFFORTLESS INSTALLATION - Comes with a foam gasket for an airtight and watertight seal, making setup a breeze.

The Polylok 18" Heavy Duty Cover/Lid is engineered for 18" corrugated or ribbed pipes, featuring a robust design with a skid-resistant surface, superior UV protection, and a foam gasket for airtight sealing. It includes square drive screws for added security and is made from durable High Density Polyethylene (HDPE), ensuring longevity and reliability.

Specifications

Material	High Density Polyethylene
Color	Green
Brand	Polylok
Style	Compact
Product Dimensions	21"L x 21"W
Item Weight	1.8 Pounds
Shape	Round
Number of Pieces	1
Is Dishwasher Safe	No
Is Microwaveable	Yes
Manufacturer	Polylok
UPC	762022552119
Part Number	3007-HDC
Item Weight	1.8 pounds
Item model number	3007-HDC
Is Discontinued By Manufacturer	No
Installation Method	Screw-In
Item Package Quantity	1
Maximum Weight Capacity	1000 Pounds
Measurement System	inch
UV Protection	Highest level
Usage	Septic Cover
Batteries Included?	No
Batteries Required?	No

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TrustScore 4.5 | 7,300+ reviews

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Fantastic experience overall. Will recommend to friends and family.

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The MOLLE sheath is of exceptional quality. Very happy with my purchase.

2 weeks ago

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NZ$224

Duties & taxes included

In stock

Sold byAmazon New ZealandDelivered byDesertcartCustomer service byDesertcartReturns14 days · 30 with PRO

Buyer Protection · Full refund if your order doesn't arrive as described.

Desertcart purchases this item on your behalf and handles shipping, customs, and support to New Zealand.

Secure transaction

Trustpilot

TrustScore 4.5 | 7,300+ reviews

Anita G.

Good experience, but the tracking updates could be better.

2 months ago

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Smooth transaction and product arrived in perfect condition.

3 weeks ago

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