Here's the table for Patchwerk hits in the old days, Back then there was a calculator for the hits to see if you had enough gear to survive it. Sadly that calculater is not up anymore. I remember our tanks needed 9k health fully buffed as a minimum for this boss approxematly. Remember the dmg on this table was his MAX hits.
Armor...Potions.................Defensive Stance........HP Needed to Survive
9000....None....................No...........................12,500
9000....None....................Yes..........................11,000
9000....Greater Stoneshield.Yes...........................10,000
10,000..None....................No...........................11,500
10,000..None....................Yes..........................10,400
10,000..Greater Stoneshield.Yes............................9,500
12,000..Greater Stoneshield.Yes............................8,500
So as someone stated erlier the best geared tanks would just about reach 10k hp fully buffed, while a good geared one had just above 9k buffed.
In burning crusade I remember it as the tanks with max hp (druids) had 25k at the end, while other tanks would go up to 21-22k?
Today we see druids have almost 100k hp in ICC with buffs, just above 70k without the ICC buff