I think you might be mixing up a couple of different things.
If you have any tIRAs, you can convert those to a Roth at any time. But note that any amount you convert is counted as income and taxed at your normal interest tax rates (so if you make $160K and convert $40K from tIRA to Roth, your income for the year is $200K, and that's what you pay taxes on). This is why many people wait until they retire to do these kinds of conversions, so they can do it at a lower tax rate.
If you want to contribute to a new IRA, your current salary would likely prevent you from directly opening a Roth, and it likely also prevents you from opening up a deductible tIRA. But what you can do now, and each and every year from now in which you have earned income, is to open up a nondeductible tIRA and then immediately (as in the next day) convert it to a Roth. If you do not have any other tIRAs out there, you can convert that tIRA to a Roth with minimal tax impacts (you pay tax only on the amount of any increase in value from the day you opened the tIRA to the day you converted it to a Roth -- which means, if you convert it to a Roth the day after you open it, there should be minimal gains). If you do have other tIRAs out there, the tax treatment gets more complex, so asterisk here.
The Roth pipeline is a big version of this that you do after you retire. Basically, you quit your job, and you roll over the contents of your 401(k) into a tIRA -- you cannot roll your 401(k) directly into a Roth, you have to stop at a tIRA first. At that point, you have, say $500K in a tIRA. You then convert part of that 'stache to a Roth every year, exactly as under the first option above -- usually, you convert what you think one year's expenses will be in a few years; the entire amount of the distribution counts as taxable income in the year you do the rollover, so you usually spread the conversions across several years to keep the tax hit low. You also have to wait 5 years before you can make any withdrawals from that Roth account, so you always want to have enough $$ available to cover your costs for those first five years.*
*I do not know whether you could combine your Roth Pipeline Roth account with your pre-existing Roth account. You existing Roth account allows you to withdraw your contributions at any time, and to withdraw earnings penalty-free after 5 years and after 59.5 -- but the reason the ladder works is that any amount that you convert from a tIRA is counted as a contribution. So as is, you could take your contributions out of your existing Roth any time, as long as it has been open for at least 5 years, whereas your new Roth pipeline will need to wait another 5 years before you can take out those contributions. Because of that difference, I don't know if you could combine them. But you could certainly very easily open a new tIRA account with Vanguard and convert that to a Roth easily, regardless of what you do with your existing Roth.