Udhhyog: Difference Between SS 304 and SS 316 – Flange Size Chart, PCD Chart, and Pressure Ratings

 Stainless Steel (SS) flanges play a crucial role in industrial piping, chemical processing, and mechanical engineering. However, SS 304 and SS 316 have distinct characteristics that make them suitable for different applications. Understanding flange size charts, PCD charts, and pressure ratings will help in selecting the right stainless steel grade for your needs.

This guide includes:

• What is SS 304 and SS 316?

• Key differences between SS 304 and SS 316

• Flange size chart and PCD chart comparison

• Pressure ratings for SS 304 and SS 316 flanges

• Why choose Udhhyog for premium stainless steel flanges?

What is SS 304?

SS 304 is an austenitic stainless steel composed of:

• 18% Chromium (Cr) – Provides corrosion resistance.

• 8% Nickel (Ni) – Enhances strength and durability.

• Low Carbon Content – Improves weldability.

Advantages of SS 304:

✅ Good corrosion resistance in mild environments.
✅ Cost-effective and widely available.
✅ Ideal for general-purpose applications like food processing, kitchenware, and structural elements.

What is SS 316?

SS 316 is an upgraded version of SS 304 with the addition of molybdenum (Mo). It contains:

• 16-18% Chromium (Cr) – Provides oxidation and rust resistance.

• 10-14% Nickel (Ni) – Enhances strength and toughness.

• 2-3% Molybdenum (Mo) – Increases resistance to pitting and crevice corrosion.

Advantages of SS 316:

✅ Superior corrosion resistance in marine and acidic environments.
✅ High temperature and pressure tolerance.
✅ Commonly used in chemical plants, medical equipment, and marine structures.

Difference Between SS 304 and SS 316

Feature	SS 304	SS 316
Composition	18% Chromium, 8% Nickel	16% Chromium, 10% Nickel, 2% Molybdenum
Corrosion Resistance	Good	Excellent, especially against chloride exposure
Strength	High	Slightly higher than SS 304
Applications	General-purpose use, food industry	Marine, chemical, and pharmaceutical industries
Cost	More affordable	Slightly expensive due to molybdenum content

SS 304 & SS 316 Flange Size Chart (in mm)

SS flanges follow ASME B16.5, ANSI, and DIN standards. Below is a stainless steel flange size chart.

Nominal Pipe Size (NPS)	Flange Outer Diameter (mm)	Bolt Hole Diameter (mm)	Number of Bolts
2"	150	19	4
3"	175	19	4
4"	230	19	8
6"	280	22	8
100mm	210	19	8
150mm	280	22	8

For a detailed dimensions chart and PDF download, visit Udhhyog.

SS Flange PCD Chart

PCD (Pitch Circle Diameter) refers to the diameter of the circle passing through the center of bolt holes. Below is a reference SS flange PCD chart.

Flange Size	PCD (mm)	Bolt Hole Diameter (mm)
2-inch	120	19
3-inch	152	19
4-inch	190	19
6-inch	241	22
100mm	215	19
150mm	280	22

Pressure Ratings for SS 304 and SS 316 Flanges

SS flange pressure ratings vary based on temperature and material composition. Below is a general pressure rating comparison.

Flange Class	SS 304 Pressure Rating (PSI)	SS 316 Pressure Rating (PSI)
Class 150	285	290
Class 300	740	750
Class 600	1,480	1,500
Class 900	2,220	2,250
Class 1500	3,705	3,750
Class 2500	6,170	6,200

Why Choose Udhhyog for SS Flanges?

✅ High-Quality SS 304 & SS 316 Flanges – Manufactured as per ASME, ANSI, and IS standards.
✅ Customization Available – Flanges tailored for industrial needs.
✅ Competitive Rates – Best pricing for bulk and custom orders.
✅ Reliable Supply Chain – Serving Delhi, Haryana, UP, and J&K.

For stainless steel flanges at competitive prices, trust Udhhyog – your reliable industrial supplier.

Conclusion

Both SS 304 and SS 316 flanges offer excellent performance, but SS 316 provides superior corrosion resistance, especially in marine and chemical environments. Understanding flange size charts, PCD charts, and pressure ratings helps in choosing the right material. Udhhyog supplies high-quality stainless steel flanges, from 2-inch to 150mm sizes, meeting Class 150 to Class 2500 standards.

For detailed specifications and bulk orders, check out the Udhhyog SS Flange Price List and Catalogue PDF.